Verified answer

The guy above me said everything I would have said. it could be the valves most likely if it on does it on 1 cylinder.

well if you tell us what the reading are i can tell you

low in one high in the next one blown head gasket

low dry bad valves

low dry high wet bad rings

low dry and low wet bad valves or valve guide

parts and labor 1200-2000 unless you have a crack head or block then new engine