1997 Chevy Tahoe V8 Four Wheel Drive Automatic 125000 miles
While driving, after releasing accel pedal, IAC counts will stay high for around 30 seconds resulting in rpm's around 2000 (verified by shifing into neutral). Eventually fall to zero and then rpm will be normal. Effect on vehilce is excessive braking force needed to slow vehicle.
For what I can tell, engine control sensors appear to be working within reasonable limits when I monitored using diagnostic tool ( also how I monitored IAC counts).
What could cause engine control module to command IAC for higher counts to cause higher rpm's when accel pedal is released?
Additional problem: cyl 3 gets 2 to 3 digit misfire counts when engine cold. Mostly goes away when engine warms up. Interesting, cyl 5 was getting misfires for some time. Then for no apparent reason cyl 5 became ok and misifres switched to cyl 3.
Recently replaced both pre-cat 02 sensors, PCV valve, rotor, rotor cap, plug wires, plugs.
any help would be appreciated,
Saturday, January 12th, 2008 AT 9:26 PM