What could be wrong causing High Idle all the time 2000-2800rpms?

you need to pull back the wire on the throttle and fix the govoner

seem for any glaring intake air leaks from damaged hoses, lacking vacuum caps, etc. tap gently on the idle air bypass valve with a small hammer or different blunt merchandise and if it idles down, replace the valve. If not, unplug the wiring connector from it. If the idle remains extreme eliminate it and block or plug the ports that are uncovered, hermetic. If the engine nevertheless idles extreme, there is an air leak someplace. If not, the IABPV remains the most in all probability suspect, even if it would want to also be a situation with the computing device or the wiring in between. flow low-priced and attempt a used valve as they don't flow undesirable that oftentimes.

You still may have a leaking injector. Also check the temperature sensor that goes to the computer,(not to the gauge) 2 wires probably a yellow and a black if this sensor goes bad it will tell the computer that it is 40 degrees below zero, and it will dump extra fuel ( this system is what replaces the choke) on fuel injected engines. Did you check the MAFF sensor if you have one? I'm not sure if IROC used this sensor.

It's probably a vacuum leak.

How to tell: Spray some starting fluid around possible points of suspicion. Like the throttle body itself. If the engine rev's then you know the starting fluid is getting in the engine and it's not sealed.

ON FUEL INJECTED VEHICLE THERE IS A LOT OF THINGS THAT COULD CAUSE THAT PROBLEM

MOST COMMON IS PROBABLY A VACUUM LEAK...THIS WOULD ALSO AFFECT YOUR O2 READING

OTHER COMMON POSSIBILITIES ARE TEMPERATURE SENSOR CIRCUIT, (SENDING MESSAGE TO ECM THAT ENGINE IS STILL COLD....INCREASED RPM)

THROTTLE POSITION SENSOR CIRCUIT, (TELLING ECM THAT THROTTLE IS DEPRESSED)

BEST THING IS TO PAY A PROFESSIONAL

THEY SPEND LOTS OF MONEY AND TIME BEING EDUCATED TO DEAL WITH THESE PROBLEMS

Sounds like a vacumn leak. Check all lines. check PCV valve

you need to check the fuel regulator spring in the throttle body to see if it broke, if it is broke it will allow more fuel to the injectors, the spring regulates the pressure

You have a vacuum leak somewhere, look for creaked/lose hose, then check your TPS.

Good luck

See if these guys can help

http://www.f-body.com/forum/forumdisplay.php?f=2

have you tried spraying WD40 on the butterfly of your carburetor. sometimes they stick real bad. you may want to also try checking your bolts and screws to the surrounding parts to make sure they aren't too tight.