i drive a 89 gxl i got it street ported i did the rebuild myself it was my first one i used the racing beat rebuild kit. so heres the problem

i got the car timed and everything great
it idels good and everything
so i put it in first gear to go as im realeacing the clutch everything is fine but
as soon as the clutch is fully engaged my motor stops giving power and starts falling back to idel. i try to give it gas when it does that and there is no responce

im stumped any ideas?