Heyy, I am reading the post, not sure you got the solution but I found somewhere that the crankshaft is not balanced good or not straight. Not sure, have read about it a year before when I wanted to buy sprinter 315 and ended up with 311 because my friend said to me that the 150hp engine has much issues. Don't know if it is caused by so much power (pressure on the shaft) or factory mistake.