Ditto....best thing to do is pull the plugs and take a look. Then, depending on how they look, you'll probably need to pull the engine and freshen it up a bit, Valve Seals, Rings, bearings, the whole nine yards. While your in there, it would be a good time to update the pistons to some forged units, maybe a cam too. Man, I think I just spend about $1500 of your money right there!
Hope all is well.