any ideas on what would cause a high idle?

My 97 2.7L Tacoma has a high idle. I dont have a tach. but I think it is only about 200-300 higher than normal. I have searched many times for a vacuume leak and found nothing, I also replaced my IAC valve with no change in idle, I disconnected my battery and made sure my coolant was at the proper level. I am now starting to think about replacing my intake gasket. anyone have any ideas that could help me out.

 

Temp sensor(air or coolant) reading within range, but cool enough to warrant a high idle, regardless of the temp. You need a scan gauge to read the temps. Compare the ambient(truck cold) temps to the engine operating temp. Compare those readings with an IR thermometer. Replace the one with the worst error.

 

If you didn't already know: Vac leaks are easy to find by spraying throttle body cleaner on the lines, and listening for a change in idle.

 

Miss adjustment is another possible cause.