I have a 94 f150 with a 4.9l I6.
My motor maintains a high idle even after it has reached normal operating temperature? The CEL comes on but no code is being thrown other than for the transmission not being in park or neutral but that never caused the CEL to come on. It has. 5 speed in it... I'm thinking it's the IAC OR THE TPS. but I ain't sure????

 

check for a vacum leak by spraying a little bit of starter fluid around the engine compartment. if it doesn't rev up its the tps

 

What about the IAC?