Need To Tune Car. HELP!

I need to tune my car bad.I have a B&M electric shift kit and no matter what setting if i hit into the gass it hits rev limiter and i have to let off for it to shift. I was thinking the pcm needs to be tuned cause i bought it from somebod and he siad something about he had some computer work done to it. Any ways what tuner should i get and what all will i need?
thanks