ripple

My various posts and much wrenching have lead me to here. After getting the motor timed, and the tps adjusted and bypassing the oil pressure idiot gauge, all is well, for a while and then I am belching unburnt fuel and my timing is off. My neighbor asked me if there were any smoke rings out the tailpipe. Yesssss! He then went on to explain that it was fuel/air being pushed past the valve, which is round. I was starting to hope that the timing belt had jumped a tooth. (It might explain the 90 to 75 psi compression test across the 6 cyls, although a little oil did jump it up 30). I am now going to check the belt and tensioner. Someone stop me if I am wasting my time. Thanks