I have just bought a 95 powerstroke, single cab long box 4x4. It has 230000 on it. The truck shifts hard when just cruising, when I give it though it shifts smooth as a baby's ***. The guy I bought it from said there has never been a chip or anything on it. All thats done to it is the exhaust cut after the cat but the cat is removes with a piece of straight pipe. Could it possibly be. Shift kit?