WHEN YOU RESET THE VALVES WAS THE LASH STILL WHERE YOU SET IT?I had this happen once and blamed it on the weather and everything else...but it got slower every pass up until a lifter broke and destroyed the engine. Looking back I think it got hurt the week before and it was telling me there was a problem (slowing down) and I ignored it...payed for it too. If any of them were loose I would look at the lifters if it is a solid roller.