02 F250 been having the problem on and off for 2 years FORD and other garages can’t figure it out. I’ve replaced all the spark plugs and coils, inline fuel filter as well as a new fuel pump truck ran great for about 7 months then started to act up again. I was also told by a garage near where I work to look at the rear module above the spare tire but they weren’t 100% sure. This started to happen after I replaced my bed on the truck from the stock to a service body. Not sure what to do or where else to look into this problem

 

Okay so we know you have an '02 gasser but that's about all we know. Need some more information on what your truck is and what it's doing. 'Issues getting onto the highway' could be a million different things.

If you've got a 5.4 and you put a service body on it, it could just be the aerodynamics of it - you basically put a massive brick on the back of an already questionable setup (5.4s in SDs have a bad rap, 5.4s need to rev high and SD trucks generally aren't geared to let it do that).

It is also a 22 year old vehicle, there could be any number of other issues cropping up from age that could cause whatever it is you're having happen.

 

Once upon a time I drove a 1995 F-150 4x4 with the 302 CID V-8. It started kind of bogging down and losing power when you had a high power demand. Getting on a freeway, climbing a long grade, passing, stuff like that. The more throttle you gave it, the slower it would go. But, it wouldn't happen all the time. One day I could drive up a hill at 60 MPH, the next day I couldn't do 30 MPH.

It was in the shop 4 different times with no problems found. I replaced every sensor I could, fuel pump, all ignition components, but the issue persisted.

Finally, one technician found that I had a bad catalytic converter. The ceramic matrix in the cat had shattered, and the chunks would sometimes allow exhaust to pass or sometimes would block exhaust flow. At high power demands, there wasn't enough exhaust flow, leading to a sharp loss of power.

The truck always started and idled perfectly. I chased this issue for 1 1/2 years before that one mechanic stumbled onto it.

So, this is free to test. Just disconnect your catalytic converter from your exhaust pipe and go for a spin. (Yes, it will be very loud). You'll know right away if this is the issue.

Good luck.