96 isuzu oasis aka honda odyssey. the van starts but stalls after half a second. few times i get stalled while running 40 mph. when i hold the key on ignition III, the motor seems running but when i leave to put it on II, motor will stall. mechanic says my engine runs smooth (he checked it while it was running) therefore not a fuel pump problem. if it is a fuel line problem, why does the motor keep running while on ignition III? is it an OBD problem? thanks in advance