Hi, new here as a registered member, but been reading for a long time. I have a 2000 GT with a naturally aspirated 3800 Series II. Recently changed head gaskets, LIM, and UIM gaskets along with a new UIM. Heads were milled. TB cleaned spotless as was LIM. Everything is reassembled, runs well when cold (although it does have a slight surge even when cold), but as soon as engine gets to normal operating temp (190ish - replaced thermostat too), engine stumbles, surges, and ultimately stalls. Replaced the CPS a couple of months ago, so I doubt that this is the issue. MAF connected/disconnected makes no difference. Replaced IAC (because it came apart while I was testing it - pintle shot right out of it), but no difference. EGR seems to work fine, I took it off and the "button" on it moves freely both in opening and closing directions. No vacuum leaks that I can find. Took the car on the road, has a ton of power again, but when I let off the throttle even at highway speeds, the RPM fluctuates between 1000-1500, and when I slow to stop at a light, or turn, the engine dies. I'm at a total loss and would appreciate any help.
Thanks in advance...
Originally Posted by def88
