I have a 94 Chevrolet C2500 that has a 21' trailer attached everyday hauling golf carts around. The problem occurs on highways when the truck is warmed up after some 30 - 100 miles of pulling the trailer. Uphill makes it worse. The truck will lose all throttle power and the gas pedal will not do anything. Feels like the engine has just died but it hasnt. It will slow down like im out of gas till i pull over. Sometimes it will make a "bucking" feeling and popping type noise but not loud. The engine idles just fine and I can pull back on the road like nothing happen. Dont even have to turn the truck off to fix it. Will do it 3-4 times a day, during a 8 hour shift. I have replaced the cat thinking it was clogged to no avail. Mechanics are stumped because it only occurs when im pulling the trailer for hours at a time. Please HELP! The truck is a 5.7L 2x4 with 132000