I will 3rd that. I had the same thing happen to me. I thought it was the battery so I replaced it but it still ran like crap and would die if I treid to let it idle down to where it should at normal. I did some research and came up with the ECM just had to take a bit to relearn. Just take it out and drive it for a while. Use you left foot to brake and keep it idled up. All will be fine.

 

So did you find out what was wrong lmm600? Did a PCM relearn fix it?

 

I had the same thing happen to my 99 5.2 sport. My mechanic changed out the idle air control valve runs fine ever since.... tiny

 

I'm really sorry I didn't respond. Actually forgot. Yes, I guess it had to re-educate itself. Basically a couple days later, probably only 2 or 3 hours running everything seemed fine.

 

Our trucks seem to have problems running well at all when the battery is nearly completely drained.

 

My auxilary reverse lights got bumped on one day at work... came out to a nearly dead battery. Tried to jump start it and it started, but it ran like crap. If the revs dropped too far, the truck would die. So... I pulled the battery, went home and threw it on the charger for 5 hours at 25 amps. When I put the battery back it it started and ran just fine.

Cartman

 

The PCM is VERY sensitive to voltage and won't do its job worth a poop on a dead/dying battery or crappy connections. Anytime you have running/idling problems check the battery/connections 1st...Free is Good!