I have a 1988 mustang that I just put a used bottom end in. I put gt40p heads along with a f303 cam and edelbrock performer rpm intake. Its been using a quart of oil every 150 miles. the oil is burning only on cylinder 6. I put new valve seals in and it still didn't fix the problem. Compression is 140 (cold) across the board. just changed the pcv valve out, and it changed nothing. oil puddles up in cylinder 6. smokes only when it gets into higher revs.