my old 302 had a moderate vibration i blamed on the flexplate i installed so my converter would fit because i dont remember a vibration before then. now i have installed a built 1974 302 with a 28 oz. flexplate & 28 oz. fluid damper and now the vibration is worse. its really bad from 2000 to 3500 rpm in park and smooths out above that. Could my converter be out of balance that much ? Its bad enough that i dont want to run or drive it. Please help!!!