already switched the plugs, tested the wires (all above 10.4) oil change, it has new belts, cleaned the maf and throttle body, it has a new air filter but its a cheapie, flushed the radiator, replaced and resealed rear diff, checked for leaks and the only one I found was the leak in the rear diff, the battery looks old, but tests consistently at 12 and the alternator is charging properly. Just putting upgrades where its needed. Thanks for the tips fellas, my main goal is to get this thing running at optimal and give it a little pep so it can get us up the mountain to Tahoe during snowboarding season.