I had a mifire problem that turned out to be ba broken lifter. I found 2 pieces of the lifter cup stuck to my drain plug magnet. What else shoul I look for while I have it apart? This happened whil driving to work on Monday, the engine didn't cut out or anything. It just felt like a miss. My oil pressure remained constant at 40 psi and never dropped below 35 psi. Thanks for any advice.