Why does my F250 7.3 diesel loses power when pulling fifth wheel? on 2000 Ford F-250 Super Duty

All is good except when pulling fifth wheel, then power loss problems.

Asked by for the 2000 Ford F-250 Super Duty
1 answer 3 comments
do you have any codes or flashing lights that come on.
No everything is fine until under a load pulling the fifth wheel camper. Thanks for your responce.
SOUNDS LIKE A FUEL ISSUE. WHEN WAS THE LAST FUEL FILTER CHANGE? THESE ARE THE BEST MOTORS AS FAR AS DIESELS GO SO IM KINDA STUMPED.F/FILTER SHOULD BE REPLACED EVERY 20K MILES ISH.
Thank you, I will try that and see what happens.