If your engine continues to idle real high after it's warmed up, check the air
regulator unit. It's located on the passenger side of the engine, below the intake
manifold, near the rear. There's a hose connecting to it. Pinch the hose when you are
having the high idle condition. If the idle speed drops, there's a problem with the unit.
Also check the electrical ground connections on the engine for looseness and oxidation.
Another thing to check for is an air intake leak somewhere along the intake plenum between the Air Flow Meter and the Throttle Valve. Check all the nuts for tightness that fasten the intake system to the engine.