maybe the timing is out, check that
and also
have you changed the plugs, wires, and cap/rotor? the valve cover gaskets and gromets for the spark plug might be bad. if you see oil in the spark plug tubes you should replace the gromets that could be why your plug keeps going bad
and also
have you changed the plugs, wires, and cap/rotor? the valve cover gaskets and gromets for the spark plug might be bad. if you see oil in the spark plug tubes you should replace the gromets that could be why your plug keeps going bad