I have a turbo 400 trans behind a 383 in my nova. Trans was just rebuilt with hughes performance clutches, trans-go shift kit, stage 3 I think. My problem is that I cannot get the trans to shift out of first at all. I have park/neutral, reverse, and first. Can bring it up to 4500 rpm and it still won't shift. Turned vacuum modulator almost all the way out and didn't change anything. Shifts fine to park and reverse and to gear, just when your driving it won't shift at all. Any ideas? Thanks in advance!