I have a 90 GMC Sierra K2500 5.7 that is giving me trouble.
Initially, with the AC on, the truck would idle low and shake at a stop while in gear. I tried replacing the IAC, EGR valve, TPS, coolant temp sensor, and one more that I don’t remember. Nothing worked and I eventually took it into a shop.
They did some diagnostics and all they could find was a dirty cap and replaced it. That fixed the shaking problem and the truck idles a bit better.
About a month later with only my fan on (no AC), while driving to work the truck died suddenly while moving. It started up fine with no codes, but I took it into a different shop for another look.
Again, they couldn’t find anything wrong with it. Fuel pressure looked good at 13 psi and he couldn’t get it to act up.
A week later, while steering with the AC on, the truck died again, but started up fine.
It still seems to idle low once it’s warmed up, and the exhaust sputters at lower RPMs. My AC growls but blows cold air. It does seem to load the engine quite a bit.
I’m just not sure where to look to try and solve this issue. The truck seems to run fine, but I don’t really trust it.
Thanks for any insight