Hi, I'm trying to help someone trouble shoot a problem on a 89 f150. It's a 302 auto, xcab 4x4 with around 95k on it.

This was a farm truck from day one that had it's oil changed only twice in it's life. Tranny was never touched, nor was any other driveline fluid.

My daughters mom (my x since 89) bought this truck as a second vehical for a cheap price. Drove it 75 miles home and it ran fine. Her husband got it home, changed all the fluids on the truck and it's had a serious problem since then. The truck runs fine all around town except when it's on the highway. Once it's goes into O/D it won't shift back out. It will not downshift on it's own. Within a few minutes of it being in O/D it will lose all it's power, the oil pressure drops and it starts knocking.

Ok, so my first thought was the tranny hadn't been serviced before and I've seen lots of problems with tranny's going out after doing a first service on it with high mileage so it's probably just the tranny. The tranny doesn't seen to slip at all, shifts fine and kicks down from all gears besides overdrive.

Note, I personally haven't had a chance to test drive the truck, this is all second hand so I'm thinking what may be happening is the motor was overheating from "laboring" to hard to pull a high gear since it won't downshift once it hits a hill.

he says the temperature gauge never goes out of normal but he hasn't tested the temp sensor to see if it's working right.

K, Now, It's never had any CEL come on but he did have a mechanic put in on a snap on scanner anyway and the only thing it read was it was 180 out of time (someone changed the wires to make it run) and it showed lower compression in 2 cylinders.

He tore it apart and fixed the timing problem, changed the fluids again, and has checked everything from front to back and can't find any problems. No brakes hanging, It doesn't use any oil, antifreeze or excess gas. It doesn't blow any smoke of any sort. It just simples runs fine one minute then once on the highway, looses everything. This truck won't pull the shirt off your back once it starts acting up. All wires, plugs, etc are all new. all bearings, u-joints, etc are all good. Fuel pressure is fine, filter is new. No intake leaks, exhaust leaks or anything like that.

They did change the exhaust to some loud cherry bomb sounding crap. I was wondering if it just might be something like once it hits overdrive the computer doesn't put the right amount of fuel to the motor causing it to run lean or something. Granted this is all guesses at this point since I haven't seen the vehical yet.

Guess what I'm asking is if anyone had any ideas of what it could be before I go start trouble shooting it in person.

Just so you know. The guy that owns it is a mechanic for Defenbaugh (trash service) so he's not a rookie. No one can seem to fix it so figured I give it a shot with some online "friends"

Please remember all "typical" things have been tested more then once. We're looking for that needle in the hay stack type of advice.

example. Had a vehical I worked on. A Expedition that was shifting hard. He had the tranny rebuilt and once it still did it he brought it to me. Turned out to be a bad DPFE sensor. go figure.

Thanks, Shawn