New member here. My future son-in-law has a beat up 96 3.9L Dakota.
Standard Trans. It failed the smog test due to High Nox.
everything else passed. Note that NOX was low at 15 mph
15 mph: 1473 RPM, CO2-15.05, O2-.16, HC-63, CO-.41, NO-0036
25 MPH: 1488 RPM, C02-15...