[nbpro]

use carb spray to check for vacuum leaks.

Your IAC (Idle air control) valve could be stuck with the plunger retracted.

A bad coolant sensor can make the computer think the engine is cold causing a high idle. Does it seem to run to rich?

Is there any other symptoms other then the high idle



From the Auto Zone site on TBI rebuilding

The easy-to-replace parts that wear out in TBI systems are the same parts that wear out in carburetors: Gaskets, o-rings, and seals, all of which are sensitive to time, fuel, and extreme changes in temperature. Since there are less moving parts involved, rebuilding a TBI system is easier than rebuilding a carburetor. If you have ever built a model airplane, then you most likely can rebuild a TBI system. Armed with a TBI rebuild kit, the task can be performed in just one afternoon. The fuel injectors themselves, however, should be tested and cleaned professionally or replaced if problems are suspected. Finally, as the complexities of TBI systems vary by manufacturer, the first step to a successful TBI system rebuild is consulting a service manual.