Rough running at times
 

Hi, I have a 2000 LS 4x4 with 125,000 on it. I have a little trouble with it when I first start it in the morning when the engine is cold. The vehicle starts but if I press the gas, it will act like it’s going to stall. The issue is more obvious when the AC is on.

I checked for codes and there are none present. I recently cleaned my throttle body, MAF and idle sensors very well, but nothing changed.

‘’When the ac is on, the idle has a hard time adjusting too, when the compressed clicks off the engine does not compensate like it once did, the idle shoots up quickly and then back down. Otherwise, it idles fine. And I am really confused because it runs great on the road and after a minute of driving the issues seem to be gone.

So where can I start?

If you have live data capability on your scanner, does the problem clear up when the vehicle transitions to closed loop fuel control?

Have you looked at any of the sensor values in live data?

Are the fuel trims different before and after it runs right?

Have you inspected the IAC valve?

Have you performed the fuel pressure test in the sticky?

George