I've got a 89 F150 5 speed. When I bought it 5th gear wasn't working but I have a replacement tranny, just no time to put it in yet. Recently the truck will run fine when its cold, but as soon as it warms up it will jump in every gear. It only jumps between 1500-2000 RPM. Is this a sign the tranny needs repalced asap or could it be something else? Engine only has 115K on it and has sat for a very long time but started every week or so to keep running right. Engine also is running very rich, which could be related or could be different, I haven't had much time to diagnose it.

 

Forgot to add in neutral and with the clutch in it revs fine with no stuttering.

 

How is the clutch?

 

New. Replaced at a shop less then 5000 miles ago.

 

I replaced the transmission now and its still doing it. The truck sat for 4 days while I worked on it and when I started it up it ran worse then ever. Kept dying on me when I'd left off the gas and push the clutch in too fast. Also jumped again... Anyone have an idea? I'm drawing a blank still.

 

Get an electrical parts cleaner and try claning the TPS and MAF. It may not fix your issue but its worth a shot and its cheap. Is the check engine light on? if so what codes?

Edit: Also go back and check all your connections!

 

cleaned the TPS and I wasn't sure where to find the MAF. Where my lines run from my filter box to the intake there was a sensor sitting right above that. I sprayed that down but I still have the problem. No check engine light.