Threw P1690 and P0336 last Sunday night before I went away for a few days (not in the truck). I just started combing the threads and Mike's articles, but haven't done any actual troubleshooting yet. Just wanted to open up a thread in case I need some pointers if I can't find in the other threads and articles. Basic symptoms at time of occurrence, though, were the tach started jumping around and then was running rough. I had seen my tach rough idling the few days preceding the codes. When the codes appeared, I was less than a mile from home, and turned around and got her home with no issues. Just got back today from a little time off and the truck did start, and the codes are still there, even after having cleared. They reappear immediately, and idle is still rough. Will keep you posted here on my progress. Mine is 1999, so it's a CKP not a cam sensor, fyi.

Sounds like you need to throw a crank sensor at it and you'll be good to go.

I'm hoping that's all it is. I picked one up at O'Reilly's few minutes ago, but will have to tackle that in the morning. We'll see.

That's what I did when mine had same symptoms. Hope it's the same for you.

Sounds promising on the sensor. Glad to hear of some success stories, vs. the alternatives of ECMs and FPCMs and (ahhh!) VP44s. I'll keep my fingers crossed. She's been running fine other than that since I put the fuel boss on, and even before the fuel boss.

Crank sensors are fairly common to fail so I would start there. Typically the P1690 will go away with the fresh sensor too.

Crank sensors are fairly common to fail so I would start there. Typically the P1690 will go away with the fresh sensor too.

The CKP on my truck (as far as I know) is the original, so here's to hoping it is just its time to go. I ordered one from Napa for $48, but got one from O'Reilly's for $78, so kind of just going to sit on it until my napa comes in, and change it out on Friday (next day off), to save a few bucks, and I'll return the O'Reilly's sensor. I need to chill out today anyway. I've been gone almost a week and really don't feel like pulling the starter motor today, that is assuming I need to pull the starter to get to the sensor, is this correct?

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Put the new sensor on a little while ago. Codes cleared and all seems okay. Hoping that was the problem. Damn, that top starter bolt is a pain to get at, especially with my fuel boss fuel lines in there. It was weird, though, I went to drive it up onto my ramps and it barely had enough power to get up on them, I guess the engine was in a limp mode due to the sensor, does that make any sense? Anyway, all is well for now.

Most likely limp mode about the ramps. If the engine can't see RPM's then the ECM is rather blind to how much fuel is given.So the crank sensor fixed the issues since the error codes are gone now.As for the starter bolts not to bad on a stock truck.