Help my 92 Ex is idling high!

[FordExplorer18]

Ok once the truck is warmed up and I put it in park or neutral it revs up to about 1800-3000 and stays there. But if I keep it in drive and shut it off and turn it right back on it idles fine. I have replaced the TPS, IAC and the computer itself so far. I have also checked for vacuum leaks with propane and their are no leaks.

Does anyone else have any other ideas? Its been 8 months now

 

[travish_1]

Did you already try cleaning the Mass air flow sensor?

 

[TPLYNCH]

Is the engine running hot? The computer will automatically bump the idle if it senses an overheating situation. Check your thermostat and temp sensor.

 

[FordExplorer18]

Yes I have cleaned the MAF and no it is not running hot.