My truck is Doing the following.....the check engine light will come on , it looses power like it bogs down and the overdrive will not engage then the light goes off and it works ok.

 

Scan the codes.

 

TPS 100% guaranteed. Happened to mine. When the TPS does not work the transmission does not know what gear to be and thus downshifts into drive for a fail safe. Do not use anything but a Motorcraft TPS for replacement.

 

Good to know aurora. Maybe thats one prob with mine.

 

It is kind of funny the truck was fine the day before. Ran great going into town come out the other side of town hit a hill and bam it jerked, check engine light come on, it down shifted and I was like wtf!!!!! Replaced the TPS and have not had a problem since. Hope this lil bit of wisdom helps you all get your trucks fixed.

 

I just picked up a dist and tfi, and I might put in the tps too.

 

Sounds good to me man. I hope it fixes your problem for you bro. I try to be helpful when I can and when I can't we you all know lol.