Mine had this same problem and it turned out to be the TPS that I had crossed off my list because I had a new one from Autozone, finally tried putting in a Mopar TPS and it fixed it

 

Mine's doing the same/similar thing. I can let it idle in park or neutral for a bit and it's like it looses its mind. Almost like theres only 3 spark plugs all of a sudden. No engine light though, or any codes for that matter. Short fuel trims are showing -99... I dunno...

 

If ya wanna know, or at least know what it ain't, try that unplugging the front oxygen sensor thing. Running hard lean is a classic symptom of a crap sensor -- the signal from a failing sensor is overly rich and the PCM is trying to haul that false reading back into line.

 

I'll get at it tomorrow. Should that upstream sensor throw a code though? Seems like it would, but I've seen some odd things go bad with no cel

 

O2 sensor won't always throw a code.... They have a variety of failure modes, that the PCM just doesn't notice.

 

I haven't ever been fortunate enough to actually see an OBD-II vehicle set an O2 code before driver annoyance has reached critical levels. The early 1980's logic that was capable of detecting the normal end of life (falsely rich signal) condition got removed because a tangentially related piece of faulty logic made owners complain too much.

Or because all of the automotive engineers on Earth suddenly got stupid.

 

Me and some of my mechanic buddies would argue that they have BEEN stupid for quite some time.

 

They were smart enough to not fight with their bosses over problems that wouldn't manifest during the warranty period!

 

They have a term for that ya know. "Engineered Obsolescence".......

Parts are designed to last just a bit beyond the warranty period. Sometimes the manufacturing process goofs, and they fail sooner.

 

It's kinda the opposite of that. The sensor technology improved to the point that they quit failing during the warranty period. That made the whole matter into a case of doan wanna, doan hafta, not gonna.

I used to have enormous good fun watching Hewlett-Packard's quality removal engineers squirm when their changes broke my junk. Their changes always broke my junk because I knew better than to try to sneak anything more than the lowest acceptable quality into the junk in the first place, but they still always made them. I don't really think they knew what they were doing and just changed stuff randomly because no one else knew what they were doing, either, and changing stuff kept the paychecks coming.