I have a 94 Ford Ranger 4.0L V6 4x4. I just had a new clutch installed last week and as I drove away from the shop parking lot the truck shuttered and jerked violently after the clutch had started to engage but was not fully engaged. It does this only when starting from a complete stop. Once I get through that 1.5 seconds of violent jerking it works beautifully through the rest of the gears. I took it right back to the shop and the mechanic told me that he had the flywheel turned and that the flywheel was borderline too thin so he shimmed it out. He said he would replace the flywheel and that should take care of it. He replaced the flywheel and the problem still occurred. Then he assumed the clutch was defective and put a 2nd new clutch in. The problem has improved some, but it still shutters quite a bit when I start from a complete stop. The mechanic is stumped and said he doesn't know what else to try. Could it have something to do with the transmission not being aligned perfectly when he reinstalled it? Or could it be my universal joint? Any suggestions would be tremendously helpful. Thanks!