I have a 91 2.3. I don't know the history of the motor but it uses no oil and runs good. But when it's cold their is quite a bit of top end noise. Quiets down if I rev it up about a half a dozen times, or let it warm up for 5 minutes or so. Is there any valve adjustment for these motors or known week lifters or rockers? This is an 8 plug motor in a Mustang.