I am adding the link in from CF. Nothing against CF or the guys helping there, just feel that the knowledge of Mopar Man himself and the guys here is incredible as well as the resources provided by the site here.
I have 99, 5 Speed, 4WD, CCLB, Motor was rebuilt at 206k, currently at 215k, New FASS Titanium Signature 165, New RV275's, VP is a different story, will mention below. No tunes.
Motor ran good in Montana and California throughout the winter. Came to California throughout the virus and since started finding problems. Keep in mind the temp differences between these places, seemed to follow the warm weather for the most part, but potentially unrelated to temps.
The primary issue I am having is the motor when coasting in neutral or the clutch pressed in/ off the throttle, will lope between 500-1000 RPM's. Usually it just kinda lops through, but recently has progressed to stalling when coasting. Once I reach 5MPH it will self correct and idle flawlessly.
It has started easy on this VP44. Initially with my rebuild I had a rebuild from thoroughbred which magically started to hard start on me three months out of warranty. I am lucky enough to have had a spare and swapped it in and no more hard start. Still have the funky coasting idle. One thing to note is the idle and hard start problem appeared together.
I have 0 codes. At one point I had the low voltage MAP sensor, swapped that for free cause I could. Code is gone, nothing else showing. You can see in the CF forum my scan tool Live Data readout. One error by my scanner software is it doesn't decipher the APPS voltage correctly. I have probed that and confirmed I have the solid 5 volts there like I should.
Cleaned my grounds. Checked continuity of APPS to ECM. Baffled as to where to go next.
My problem seems too much of an "electrical" issue to me, however I am eyeing a new tank of diesel. What are the mechanics behind bad diesel being potentially causing this issue? I have had the same tank of fuel for the past 1000 miles (I have a bed tank plumbed into my main tank- 2500 Mile Range). Thank you all in advance for the help.