My 1988 V6 Pickup has been running rough for a bit now. I had assumed a burned exhaust valve somewhere, but a compression test suggests something else. Cylinders 2-4-6 are reading about 155 (2), 165 (4), and 170 (6) psi, but the 1-3-5 side are all almost exactly 112psi. Would this be a head gasket or perhaps the timing belt slipped? It has been about 60k miles since the last valve adjustment which made me think burned valve. Any other things to check???
