I have a 1995 F250 with a 351. It has 154,000 miles.
I just replaced the heads with reman units from Napa. Also, the cap and rotor, spark plugs and spark plug wires. I put Hooker long tubes, an H pipe and 2 chamber flowmasters on it. It has factory 3.55 gears and 285/75/16 Dynapro tires (brand new tires).

Before I did all this, when you hit the gas it would hesitate at any speed. If you were going 40-60mph it would just stumble and sputter and accelerate slowly if at all.

Now with the repairs that problem is mostly gone. Going 40-60mph if you hit the gas, it moves but you can still feel a slight studder. It feels like its popping inside the engine. It will accelerate now, but not very fast.

Also, I pull a lawn trailer and tractor (about 1600lbs total). With the overdrive off, it will lose speed going up hills. It's a challenge just to maintain 55mph.

After about an hr of driving with a trailer, the trans from a stop will shift quickly through the gears and not take off fast. What is going on there?

I know these trucks are not powerhouses! But I feel like it should run better and pull harder after these repairs/mods. I want to pull a 27 foot camper with this truck next summer, and right now I know it wouldn't make it.

Any advice on other areas to check for problems?? Throw some 3.73 gears in it?? THANK YOU! _Jamison

 

Could timing be an issue?

 

First step will be to pull and check for codes.

 

how to check for codes

 

Also check fuel pressure.

They're not powerhouses but with long tubes and good exhaust the 351 has enough ***** to pull 1600 lb trailer without any slow down.

You obviously have something wrong, you'll be pleased with how good it runs after you find and fix it.

 

Ignition coil, had the exact same symptoms on my truck. New coil fixed hesitation and sputtering.