Ahem, Uhh, NO. Leaning out the mixture will cause the combustion process to be hotter, which *encourages* the formation of NOx. IF, and I say IF your HC reading is *very* low, try RICHENING the mix a little. Your HC will go up, but the NOx will come down. Changing the oil will help a little, usually more with HC, but itís worth a shot.
I donít know about the Federal versions of the 1985 cars, so I canít comment on whether it should have EGR or not, but it seems likely that it should. If it is a gray market car, it may have been mickey-moused. My Euro Rust Bucket V-8 had the frequency valve (part of the 02 sensor feedback loop) jury rigged into the control pressure line coming from the warm up regulator. An aftermarket mixture controller controlled it. This set up will work to some degree, at least in theory, but by controlling the center plunger pressure (via the control pressure line) it will not have as fast of a response as a system with the proper fuel distributor and pressure bleed point. Talk about Mickey-Moused, this was on a 1978 car which didnít even need a 3 way catalyst!
You might try some of those ďemission passerĒ snake oil gas additives Ė Iíd be curious as to whether you get any results from those products. I would venture a guess that they are something to make the fuel more volatile and therefore more easily fully combustible. Who Knows. Not Me. I donít know anything this late at night