1996 4.0 explorer revs then idles normal then reves again

[brindlpitt1]

Well like the title says I have a 1996 ford explorer 128,000 miles.
starts just fine , has no check engine light.
sometimes when you start it it revs to 2500 + rpm not always
But what it always does when you put it in gear it revs then idles normal then revs again then idles normal and if your not holding the brake it runs down the road about 30 mph with out touching the accelerator

as long as you sit holding the brake with it in gear it will continue to rev up then idle normal then rev up ......and so on and so on and so on

runs down the highway fine, gets about 16 mpg. everything else seems normal

any one else have this problem?
what fixed it
I tried searching the forum but dint find any thing like this.

 

[1992fordgreen]

This sounds like a slow Transmission solenoid. The engine has free running until the solenoid figures out what to do next. Being slow, it's not fast enough to automatically and smoothly go into gear. No CEL/OD light?

EDIT: You also might want to check the PCM, and the TPS.

 

[brindlpitt1]

It goes right into gear and if your not holding the brakes when the engine decides to rev it drives off.
its just like your in gear holding the brake with one foot and pressing the accelerator with the other then it stops then it does it again and so on and so on

 

[koda2000]

have you tried unplugging the throttle position sensor? you can also try unplugging the MAF and IAC.