Jasper motor installed, now it hesitates
 

I installed a jasper in my 95 blazer, now after driving for 10 to 15 min It has a hesitition or bucking feeling to it. i'm a 15 year mechanic and I'm having a problem finding the problem because it only does it when driving. Maybe about 10% throttle, no codes, can't get it to do it in shop or even power braking. Used an install kit w/motor. Checked all my wiring. Scanner shows nothing, good fuel trim, no codes. I have got to be over looking something loose ground ? Any remember how many ground wires are on the back?