you might re-check your rocker arms as well. Make sure that they are not too tight. That will KILL power and if they are too loose, you will lose power as well but you would be able to hear them if they are too loose. I am sure thatothers will post how they adjusted theirs but if you loosen them until they make noise and then tightenm them just enough to shut them up and then an extra 1/8 of a turn, that should do it. You want them as loose as possible with out clacking.

something to check anyway.

NightTrain66