must have had a bad ring or oil getting in to #1 and #2, plug was real bad after only 500 miles, 1/4 inch of black oily stuff on the plug. Got the engine rebuilt in the 93 5.0, and tuned, last month. guys did great work, they specialize/know stangs very well, just north of Austin, called Motion Dynamics Car stays in low temp range now, and no det at full boost, 8# KB New summer tires did the trick too. the Fast days are back! next is paint (poor thin paint on old cop car), then pipes.