I'm needing some help with my '97 F-350. When sitting or driving without a trailer it seems to run fine. When pulling a load, such a a large camper, it loses all power to rev above 2000 RPM. The fuel filter has been changed but the problem is still there. It does the same thing whether on the front or the rear tank. It seems to be a little better when running on a full tank of fuel. Could it be the fuel pump? Does this truck have any pumps in the tanks or is it just the one on top of the engine? Also, the pump on top of the engine is a strange looking critter. Is it liquid driven or what?

Thank you,
Sandy Dailey