So my truck has always had a miss since I bought it. But I occasionally I put some head gasket seal in it and it has always been dependable. except for fan clutch bearing going out. replace and fine, ran for another year. day before thanksgiving I'm driving down the parkway and it starts losing power. I push the gas and rpms go way up, delayed and hard shifting but no speed gain 55 mph tops, temp gauge starts to rise. stalls a few times but eventually starts again with the help of a jump. after traveling some more because I had to make it home it stalls again while stopping at red light, would turn over but not start. replaced the water pump again and new battery and still turning over but not start. some backfiring causing cover on air filter to pop up. sounds steady but obvious it's not going to start then it completely shuts down turn the key and nothing won't turn over at all.
my first thoughts are timing, starter relay and spark plugs. any insight? I need my truck!!!

 

Welcome to FTE.
Scan the computer for trouble code clues & post All code Numbers, as they can help focus a trouble shoot.

Edit: Might also be helpful to know the mileage on this puppy & where you are on All past & present due scheduled maintenance replacement parts, filters & fluids.

 

Pawpaw is correct, we need more details about your truck to give you better advice. In the meantime I believe your thoughts are correct, sounds like it jumped timing. Neither spark plugs or starter relay would cause it to just lose power while running. Although remote your problem could be a bad torque converter, a loose crank position sensor or failed fuel pump.