My truck started losing power under load. It wouldn't accelerate. The engine would return to idle without dying. This first happened a few times when in tow mode pulling my 4000 lb trailer up a grade. It then happened the next day in eco mode with no trailer attached. Of course, now that the truck is at the dealer it's not happening. The service manager suggests it could be fuel pump related. I'm concerned about safety. Is this going to happen on the freeway? Thoughts? Suggestions? Thank you for your responses.

 

Intermittent problems can sometimes be a real pain.
Many times there will be a code in the vehicle computer showing the system malfunctioning.

That is as good a place to start checking as any .