My 99 used to pop into neutral from time to time, I installed a shift kit and it cured the problem. You guys think that could possiably have something to do with his problem?

 

I amnot forsure where to start but I have looked around and can't find an answer. Mine just started doing this. Not forsure if it is the same but what could it be? When I am steady accelerating and shift to 2nd gear I can only go to 7k rpm. then it drops to nuetral. If I only 1/4 to 1/2 throttle I can go all the way to read line. Has anyone else had this problem or heard of this. it only happens in 2nd. what is the fix if you have had this or heard of it.
thanks
Joe