rasputin

So the car ran great for about 1500 miles, and now for the last 300 miles, it has not been idling well. From what I can tell, the idle is set at 800rpm, and goes down from 790rpm to 840rpm as it lopes when its working correctly. Now it does one of two things; idles in the low 700's then tries to pick its self up back to 800 and does so after about 10-15 seconds, or idles at 400-500 and tries to bring its self up and sits around 600, then after about 10 seconds brings itself up to 700. WTF

The unusual thing is I can tell when its gonna do this. It doesn't always idle wrong which is the thing that gets me, although its been getting worse everyday that goes by. Ideally I start the car it either does its usual 1000rpm warm up to 900 rpm, and then 800rpm. I can tell when its not gonna idle right because it doesn't do the 1000rpm jump and just kinda sits around 700. I hope that makes sense, I will try and get a video of it.

When its not idling right, when I get off the gas in gear and let it engine break, it backfires below 2500rpm.

Interesting Facts:

*Doesnt always idle bad, maybe one in three times of starting the car.
*When idling bad, the car backfires
*Car was fine for 1500 miles, now does this
*Got much worse when the new racetronix kit was installed
*New opti - car is smooth all the way up to 6200rpm
*New plugs, wires - feels fine once the car is driving, but not idling

OBE1 95Z28

Check for vacuum leaks. Might also want to clean your IAC and the associated passages in the TB.