While driving my 97 F250 PSD at highway speed, I suddenly lost power. I could run about 55 mph on flat gound (pedal to the floor), any 40 or less on slight inclines. I could feel a rough vibration from the engine at stop lights. I knew the fuel filter was overdue for a change. That be change the truck acts like it run on four cylinders. I guess my question is where to start looking.

Thanks
Sam

 

Sounds like you may have burnt a valve cover harness. Unplug each connector one at a time with the truck idling. If its good the truck should start running rough(or rougher!). Also look at the connectors for damage. Some also say if you remove your oil fill cap and take a smell you can smell if its burnt?? I dunno about that one??

 

I had the same problem with mine. It was the valve cover harness. The hotter the
engine gets the worse it gets. The heat causes the connections to spread and
seperate. So once the engine cools the engine runs fine until it gets hot again. So
if you replace one side you might as well replace both. If this helps you out at all.