The 426 just got a boysen excelorator pump cover and a home made power now insert. I started it up seemed fine. I drove it to a open field hit full throtol and it almost stalled so i let off thinking it was too cold and rode easy for little while. I was coming to a turn and pulled in the clutch and it just starts reving on its own getting in the high rpm. After a couple seconds of it reving on its own it went back to normal. it did that off and on. So by now ithought it would be heated up enough so i gunned it coming out of a turn and it started cutting out. It has no power after half throtol now. The low end feels good but some times when I shift it bogs for a secont but only some times. But like i cant give any more than half throtol or what it does is looses almost all power and starts poping loud or else it just looses ALL power and roles till i let off. So whats the fix?