95 F150 idles high at times, when driving it does'nt want to shift, unless you run it up to 27 mph then let off the gas. then shifting to 3rd gear you have to run it up to 55 mph, and let off the gas. problem started all at once. engine runs smooth as silk if you just crank it up and let it sit.

i'm confused! Any Ideas? Thanks!

 

I am 99.9 percent sure that your truck does not have a vacuum modulator on the transmission. Look at the throttle body. There should be 2 possibly 3 cables attached to it. 1 is the gas pedal. 2 is the transmission detent cable and 3 if its there is the cruise control. Make sure they are all attached and not broken or binding. If the tranny detent is binding internally it makes the tranny think you are at a higher pedal pressure than you actually are. IF its off it has no clue what the gas pedal position is in and shifts whenever it wants to. If by some freak of nature you have a vacuum modulated tranny. There will be a vacuum line going to the tranny to a valve on the right side or the back of the tranny just over the transmission pan. I just do NOT think you do.

 

Makes sense, I recently did a tune up, and replaced the valve cover gasket. So i had the upper intake off. The problem started soon after that. I'll look at what you suggested, and post back.
Thanks Man!