ok this is about to drive me crazy. The car wont get over 3900 rpm and it start studdering when it gets there. iv checked for vacume leaks on the upper and lower intake. I have even taken it off and re torked it with new gaskets, and checked it for leaks again. i have replaced the map sensor the tps sensior. the firing order and timing is correct. ohh and its a 86 and the motor came out of my 87 which it was running fine in when i took it out. also the 86 didnt have this problem with the old motor.