Howdy everyone,
Was looking for some ideas about my 99 k1500. When I am driving and have the A/C, lights, and radio all on, once it gets hot, she likes to idle around sub 500 and make heavy RPM drops when I take my foot off the gas. I noticed for a bit that the gear would disengage when I came to a stop and it would idle at 400 but I figured that was because of the low idle. However, If I go to make a turn and take my foot off the gas, when I turn, the RPMs drop significantly and she stalls out. I just put in a new distributor with cap and rotor today, and an alternator and new plugs last week. I had gotten 3 different alternators that kept failing the charge under load test from the AutoZone tester and figured the alternators were good. But when I was measuring the voltage on the new alternator to the battery with a buddy revving the engine and turning the wheel, I noticed it was about low 13s and was not sure if it is maybe worth replacing the wiring as it is most likely original. The throttle body has been cleaned and I replaced the TPS and IAC a couple years ago. I think the issue has been going on for about a year. I thought my wife was crazy because I'd never been able to duplicate it until I handled some other small issues. At this point I am thinking it is an electrical issue since everything anyone has suggested to me has been cleaned, tested and works, or was replaced. Any thoughts would be greatly appreciated.

 

Any luck fixing?

 

I replaced the cable from the battery's positive to starter since it was corroded like crazy, new fuel filter, but saw no change. I ended up taking it to a friend's shop and they realized the thermostat was locked open which wasn't letting the computer relearn. I replaced the thermostat and coolant temp sensor and everything was good as new.