I have a 1997 6.5 3599 GMC. The truck does fine, plenty of power as you have accelerate. When you are on level road with no power on the truck it miss and cuts out. I changed the PMD , no luck. If you push the truck it runs fine. I need help!

 

Interesting. I would suggest checking lift pump pressure for starters. Hook up a psi gauge to the diesel bleed hose on the front of your engine. Then open the bleeder. If it is reading less than 7psi you are getting inadequate fuel. Maybe a clogged fuel sock in your gas tank. At least you could rule it out.

 

How Many Miles I'd Replace The Lift Pump And Drop The Tank See If You Got A Clogged Sock And FLoaties I'm Your Tank I Had To Replace Mine Because The Coating Was Flaking.Off The Inside And I Would Change The Fuel Filter And Inspect The Inside Of The Housing