I recently bought a 2002 Ford Taurus with 120,000 miles. It had a bad engine miss caused by low compression (40 lbs) on the front head. I first replaced the front head which fixed the # 5 cylinder miss fire. The engine still missed because the # 1 cylinder was 60 lbs. and the # 2 was 120 lbs. I changed the back head and the engine runs fine. I looked at the intake valves and the surface was pitted on all of the valves. The exhaust valves looked good. The head seats were fine. I talked to the local garage and they suspected that E85 had been used by the previous owner. The E85 will increase cylinder temperatures. Is E85 the cause?