1994 dodge ram 2500 5.9 4x4, 150,000 mls.recently tuned up. My truck is idling and running very rough. Fuel mixture appears rich, new plugs are carbon fouling.No check engine light and no trouble code, check engine light and trouble code diagnostics work. I unplugged the MAP sensor connector and a few others momentarily and verified some codes. However the trouble codes do not respond to the exhaust oxygen sensor whether plugged in or unplugged. Anyone out there have any ideas ?