Well last night while cruising, my car developed a high 1500rpm idle. It lasted for about 10 seconds, then went right back down to 500. Before that I've been noticing a hanging idle, all I took the iac off and noticed it was full of carbon. This morning I bought a new unit, put it on, cleaned my throttle body, and fired it up. It's maybe worse now. I push the clutch in and it raises a few hundred rpms, drops to 1500, stays there for awhile before settling back down to 500. Any ideas here? I have an Accufab throttle body and plenum, bbk cold air intake, and exhaust on the car with an sct eliminator chip. This is really annoying.