I have a weird stalling problem that I am trying to fix. My car idles fine just sitting but when I come to a light and push in the clutch to stop, the RPM's will fall and over shoot my idle (850) and the car almost stalls and then the IAC tries to recover and it surges for a few times trying not to stall before it stabilizes at 850 again. Sometimes it flat out dies. The odd thing is, it works fine for about 5-10 mins. every time you start the car. For example. If the car is fully warmed up and I'm driving and I come to a light and motor dies, when I restart the car it works fine for a while. No stalling. Then about 5-110 minutes later, it starts doing it again. I have even raised the rolling idle to 1050. That also works fine for the same time period and then stops making a difference. After a fresh key cycle, idle hangs at 1050 and then drops to 850 after a couple seconds. Once she starts acting up, this no longer works, Car goes straight to stalling upon coming to a stop. I can be at 1500 rpm, and put in the clutch and she'll stall.
Here some info on my car. 406 ci LS3 with ported 243 heads and Fast 92. Nick Williams throttle body with the remote IAC. I have a very short Air path to the IAC which is hooked up to the vaccum port on the passenger side of the MAF where you usually hook up the PVC line. This is a large orifice so I would think It would flow enough air. Cam is a 239/245 .610/.627 112+2. Car idles fine on its own with IAC off and spark help off. IAC values are low though, around 30. Just revving the car up in Neutral has similar results. Works fine and has a soft landing for the first 5 min. or so and then once the IAC counts fall to 30 and stop dropping, that is when it starts to over shoot after a rev.
My tuner has tried to fix it but everything he does seems to only affect the way it behaves in those first 5-10 minutes when the problem is not these. Once that magic amount of time or something passes, it starts stalling again.
heres my current tune.. I'll post a log in a few.