The problem might be with a defective Idle Air Control valve.
The next time the idle is high, locate the IAC valve and tap on it with the handle of a screwdriver. If the idle speed changes when doing this replace the IAC valve.
Tester
The problem might be with a defective Idle Air Control valve.
The next time the idle is high, locate the IAC valve and tap on it with the handle of a screwdriver. If the idle speed changes when doing this replace the IAC valve.
Tester