Need some help. I have an issue with my truck where it will progressively hiccup then stall. Truck is a 99' 2500 auto 4wd shortbed

If I start the truck and change to gear, after 4 minutes truck will start hiccupping and it will hiccup in intervals of exactly 5.4 seconds where they progressively get worse. After about a dozen or so it's bad enough that it's able to stall.

If I start and stay in idle, wait 5 minutes, change to gear, it will immediately stall.

The predictability is truck start -> 5 minutes pass -> will stall.

However:

I can circumvent it by applying and holding throttle for about 5-10 seconds. If I do this before, during, or after that hiccupping cycle starts, I can drive like normal for however long I want with no issues. But once the truck is shut off, depending how long I wait to start the truck again, it will either immediately stall or go back to square one. The sooner I start the truck, the sooner the cycle starts. Overnight, the hiccupping will start after 4 minutes.

So, this issue happened 3 years ago as well. Now is the time to mention I had, and have again, a P0216 code. Last time, after I changed the factory APPS sensor to the WELLS, everything ran smoothly and the code went away and all issues went away for over 2 years.

Currently, the WELLS APPS is set to .533v. The original was labeled .536v before being replaced.

Fass lift pump steady at 14-15psi.

Restarts immediately after stall.

Alternator outputs 13.5-14v.

Potential issues:

Live throttle reading is between 10.2% and 73%

Truck will not reset APPS. Remains 10.2%-73% after multiple attempts.

While live throttle reading is stable with key on, engine off, with the truck on it oscillates ~9.8%-10.2%

Troubleshooting so far:

-I've tested the APPS sensor voltage while the truck is on and off with a multimeter and it remains stable, even during the hiccups/stalls. While all measures don't point to it being the cause again, a replacement is on the way just to rule it out completely.

-I've tested the idle at 6v and 5v. Symptoms change a little but remain.

-I've done the W-T mod. Nothing changed.

-I've re-cleaned each and every ground cable and terminal. Nothing changed.

-I've wiggled the cables while measuring, APPS voltage remained steady.

Does anything immediately ring a bell and sound like something you think you know what it is?
If not, where do I go from here?

Thanks for all the help.

Good information on your first post; however, I am not sure what a "hiccup" means - could you elaborate on that description a bit more?

In the meantime I will refer to "hiccup" as a symptom. If I understand your symptom correctly, it only happens a few seconds AFTER the transmission is shifted into gear - never right when it is shifted into gear. Is this correct? Trying to figure out if this is a transmission related symptom or an engine control related symptom.

Also, are you saying that this same symptom occurred 3 years ago along with a P0216 DTC? Just confirming. The P0216 code concerns me.

Is the mechanical set screw for the throttle cable secure? Have you confirmed that the idle validation part of the APPS is working properly?

• John

2 hours ago, Tractorman said:

Good information on your first post; however, I am not sure what a "hiccup" means - could you elaborate on that description a bit more?

In the meantime I will refer to "hiccup" as a symptom. If I understand your symptom correctly, it only happens a few seconds AFTER the transmission is shifted into gear - never right when it is shifted into gear. Is this correct? Trying to figure out if this is a transmission related symptom or an engine control related symptom.

Also, are you saying that this same symptom occurred 3 years ago along with a P0216 DTC? Just confirming. The P0216 code concerns me.

Is the mechanical set screw for the throttle cable secure? Have you confirmed that the idle validation part of the APPS is working properly?

• John

Thanks for the reply. I'll do you one better, here is a video: https://youtu.be/xlBDX3KDxIs

I suppose you could say "lope" instead? How would you describe it?

After putting in gear it will stall immediately (if it's at that point).

Yes, the P0216 code came on 3 years ago as well. Replacing the APPS sensor in that moment at minimum got rid of all the symptoms, and now they are back.

Attached photos of the screw. Unfortunately, it's too secure. I'd tried seeing if I could adjust it before and it just breaks bits.

I did further testing with the alternator yesterday. I thought I had hit the jackpot, as when I removed the cable and went into gear, I got no stall. So, I replaced the alternator. I tried again and got an immediate stall.. bummer. But I couldn't get it to stall again yesterday evening, progress, coincidence?

Before the ac noise between negative battery and alternator post was about .035-.045. Now it's .032-.042. (between battery terminals it is .026-.035) Jumper cable between negative batteries doesn't change it. Could it actually still be the alternator and the ac noise from the new alternator still just be too high?

I tested the truck this morning. Starting, putting in gear, waiting 4 minutes and it occurred again. I disconnected the alternator, but it stalled. Reconnected again, and couldn't get it to stall again. It could be that once the sequence starts, it needs to finish it? I couldn't get it to stall again. Tried 4 hours later, can't get it to stall. Will try again tonight.

I can't confirm the idle validation yet. The scan tool I have currently isn't good enough. I should have a scan tool in a day or two capable of testing that and more if needed.

Good idea posting the video. I listened to it several times. To me, it sounds as if the engine fueling is being momentarily switched off (no fueling, falling rpm) and then a split second later switched back on (fueling hard, to catch up to idle speed). It doesn't sound as if a heavy load is being placed upon the engine. As time progresses, each time the fueling is switched off, the duration (off) seems a bit longer until finally it cannot catch itself, consequently the engine dies.

A most unusual problem.

There is an ASD relay (automatic shut down) that is tied into the controller on the VP44. Blue Chip Diesel talks about this. If pin #5 (VP44 controller) has voltage present, fuel will be shut off. Supposedly, the ASD relay is a fail safe that protects the engine (such as when no engine rpm is sensed by the cam / crank sensor).

The ASD relay (#59) is located in the PDC. You could swap it with the AC relay to see if it makes a difference. Also, Blue Chip Diesel mentions that some people cut the # 5 pin wire on the VP44 controller.

• John

https://www.bluechipdiesel.com/runningtests

I believe that is an accurate assessment.

So that was an excellent idea about the ASD relay. Unfortunately, it works exactly as it should.

When testing with the Meter, no 12v firings were measured when it was cutting out. It remained steady at 0.112v until shutting off the truck with the key and it went to 12v for, interestingly, 14.5 seconds (not the 3 seconds according to that write-up)

However, the cables are in somewhat rough shape. 4 of the 6 are a bit frayed. The physical wire’s themselves seem ok except the ASD, it has about half the strands cut (a little further up than where most of the bare copper is in the photo)

Edited Monday at 04:04 AM1 day by Jordan_

I know that Auto Computer Specialist actually rebuild wiring looms.

https://mopar1973man.com/forums/forum/210-auto-computer-specialist/

The voltage of the APPS seems low at .112 volts. I would suggest getting a Timbo APPS and ditch the old voltage APPS of the OEM and Wells (Magnetics). Timbo APPS is a true mechanical APPS.

On 2/14/2026 at 4:29 PM, Jordan_ said:

Currently, the WELLS APPS is set to .533v. The original was labeled .536v before being replaced.

Bad idea.. Again, that is not how that system works. That voltage is determined by the sensor; each manufacturer is differen,t and the value never matches!

Edited 9 hours ago9 hr by Mopar1973Man