sorry for the long post, but i feel it's helpful if i give as much 411 as possible before posing a question:

this is what i have done to my sorta new to me f150 185000 (3months. when i got it i felt that there was very little power for a 351. i drive a 1991 3sp 302 2x4 as a work truck, and granted, it is a different truck altogether, but the work truck had much more pickup than my pickup.

-rear drive shaft u-joint
-tranny flush, filter and pan gasket (emptied torque converter)
-engine oil/ filter change
-coolant flush (did not do the engine plugs, just the lower rad hose and drain ****, actually flushed the system a total of 10 times), refilled with 50/50 mix
-new generic spark plugs (gapped .044), wires, dist. cap and rotor (all napa brand)
-compression test, all results (engine up to temp) within 185-200 psi range
-base timing (with SPOUT connector unplugged set at 10 deg BTDC (was at 10 deg after TDC)

i feel like the truck runs a ton better, but was wondering if anyone can suggest other tests, or the like, as i want to take this truck and pull a 5000 lb trailer to the southern tip of baja ca, 3000 miles round trip, with a few passes to climb. i'm looking for best fuel mileage i can get, and as much power from this truck too. i probably can budget another $500 towards this.

-what do you think about upgrading the ignition system, or even just sidegapping the plugs?
-i don't have to pass smog for another 2 years, will removing the cat (s) make a difference?
-any other suggestions? i have 31x10.5 tires on it now, the stock size is 265 75 R15, gearing is 3.55.

thanks so much, really looking forward to your responses, mike