HELP! I have an 79 Caddy 5.7 (olds) I need fuel press. specks! The veh. has an auternating miss on clys. comp. test at avg. was 135psi per cly. fuel press @ 10-15 psi, spark plugs fauled (black) blows black smoke, runs better cold, still misses. backfires out ... Login to read more.