Dcrow

I have a 95 Formula with the LT1, I had it bored 30 over and stroked to a 383 and a little bigger cam. I changed injectors from 24lbs to 36lbs. Every thing on engine is new, sensors and all. Problem is I have bad viberation that seems to being caused by possible misfire. Machine shop has checked everything to make sure its not a balance issue. Found plugs were very black so changed back to 24lb injectors and put in new plug and runs worse now then before. Not sure where to go from here.