Interm. no power in reverse

[Chappy509]

1st post on this forum. My buddy and his business partner have 3 powerstrokes. One of them is a 2002 F350 7.3 Dually with a flat bed, bone stock. They do alot of snowplowing and sanding in the winter. Once in awhile when put into reverse it will have no power and can barely get out of its own way.I have not duplacited the concern myself but he says it happens here and there. It has no DTCs, I thought it may have a broken engine mount and pulling on part of the harness causing a short/electrical issue. But it doesnt have a broken mount and harness appears to be ok. He has had it to the Ford dealer and they charged them $275.00 and said they didnt know what was wrong with it but thought it needed #8 injector, which i disagree with, and they wouldnt back up the work. Didnt know if any of you Ford buffs have seen anything like this or have any good input.
Thanks alot

[Chappy509]

No helpfull input??

[PHPDiesel]

Does it feel like the torque converter clutch is applying in reverse? It's a common problem with a failing pump or internal seals that are leaking.

[Chappy509]

Not sure, I havent duplicated issue myself. Have seen it happen 1 time with owner driving. Sounded like it was in limp mode. I suggested it may have a trans issue. Trans was replaced 1 1/2 ago (which i know means nothing). The ford dealer that looked at it and doesnt know whats wrong with it said it is NOT a trans related issue. which i dont agree with, cant rule it out. I guess i need to drive it some more to try to get it to happen. I know it is hard to try to dio an issue that you have not dupliacted, and that has become my biggest problem, due to owner thinking that there is something wrong with it.