It can be, but it doesnt have to be there. Do the tests that have been mentioned and that should give you a good indication of whats wrong. Pull the plugs and see what they look like.

Dan

92 Rodeo, 3.1 TB crank, custom bumpstop spacers, DOR shackles, Flipped ball joints, D44 Rear, 4.56s and new magnaflow cat and dynomax ultraflow muffler Since been replaced by a 2 door Explorer on 31's shackles, cranked torsion bars and full exhaust