I have a 03 F-350 Superduty V10 and the other day I noticed it loosing power when I pressed the gas at about 65mph. It was like hitting the rev limiter at low RPMs. Then it would do it at 55mph then 45mph then 35mph for about the next 10min. until I could barley move. The next day I noticed it would run fine for about the first 20min. then it would do the same thing. It seems as if heat plays a big part but my trucks temp is fine and no service engine lights come on. I had this problem with an older Chevy truck and it was the fuel filter in front of the carburetor. A friend said it could be the Catalytic Converter, how do I check? Thankx, Jimmy

 

Welcome! This should probably be moved to the Super Duty forum.

I answered you duplicate post in the Excursion forum. That one may get moved instead and this one be removed.

 

Welcome to FTE Jimmy.
While there are afew forums you can post in a good start is the Modular V10 (6.8l) : https://www.ford-trucks.com/forums/forum49/
Swing by your local LA chapter and make some noise in that forum: https://www.ford-trucks.com/forums/forum148/