I am no mecahanic and i do not want to drastrically modify the engine. I seems to be sluggish. What can I do to get some more power? A good tune up help?

Also waht type of drive train preventative checkup do you suggest? Is it a good idea to pull the plates on th differentials, transfer case etc and check them out?

FYI, I have a F250 1990 with just less than 92,000 origianl miles.

 

You can start by putting a Ford motor back in the truck.


Funny guy right.. I bet you meant 302. Congratulations..you have the weakest motor ever put in these trucks and you have a big heavy truck, so it'll never be monster. What condition is the exhaust in? If it's stock and very quiet that's your first problem, it's about as close to a cork as an exhaust system gets, remove and/or replace as much as you can. Some guys hollow the cats, but I'd recommend replacing them with a high flow version.
Advancing the timing will produce more pep, might be a good idea to check the timing anyway, factory setting is 10deg BTDC, and you may be able to get away with 12-14deg. If you just acquired the truck it's a good idea to pull the codes to see if it has any issues, see here fora DIY method... Ford Fuel Injection. Outside that a good tunup will keep it in good running order, plugs and wires, filters and fluids, and some injector cleaner.

 

If you don't want to get into the engine, I would suggest regearing. Check the to see what gearing you have. With a 90 F250, you've probably got 3.55. Is it 4x4?
Do a good tune up first. Use Motorcraft copper plugs, Motorcraft 8mm or Ford racing 9mm wires, and Motorcraft cap and rotor. Do not use a Fram oil filter.