1995 Taurus failed emissions - high NOx level

1995 Taurus SHO 3.0L with 123,000 miles. I posted before about engine cutting out when a/c is on. I filled up with oil (car had a small leak) and it started working.

I torqued the bolts on the oil pan just like the tech here suggested (up to 106 inch pounds). It helped a little but there is still fresh oil on the engine that you can smell burning a little when I get off the highway.

Not much of a leak at all (less than a 1/2 qt every 1200 miles). The coolant light went on so I filled with coolant. Driven about 500 miles and level has dropped slightly, not much - still at a good level - but noticeable.

Took car to get emissions test. High NOx level - 1622ppm (vs 796) at 25mph and 2041ppm (vs 879) at 15mph. Everything else way below the standard. Researched this online and it is usually caused by high engine temp. Unless my sensor is bad - engine temp always on the low side if the guage. No coolant leak, I don't smell it burning and I don't see any white smoke from the exhaust.

Any ideas on what to look for? By the way - car performs great so it doesn't feel like the plugs or any timing issues (if that could happen on the car. I really have no clue but that is what my dad says).