First of all, reset the ECU. Then check to see how far open the throttle plate is, and if it's getting held open by any differences in the throttle cable or throttle cable bracket position. After that, look for vac leaks. It can't idle at 5.5k unless it's getting a pretty decent amount of air, so you need to figure out where that is coming from.

You're going to need to get tuned also. You've changed enough things that you shouldn't be running stock maps and fueling parameters.