i have 96 civic cel light keeps telling me misfire. i have changed cap,rotor,wires,plugs,coil.icm. adjusted valves,cleaned injectors,cleaned thottle body, and runs better just doesnt idle good. compression on #2 cyl is 90 compared to 180-170 in other cyl. stopped at a mech. to see what he thought he thinks head gasket valve job. if i take oil fill cap off can here air. can any one help??