Car idles rough with a noticeable miss when cold. Once it's warmed up, it idles very smoothly, but the idle speed seems to wander (as high as 1100 or as low as 600). I did a tune up (NGK plugs, Nissan wires, cap, rotor, air & fuel filter) and adjusted the TPS. No change. I messed with the idle speed screw and it didn't seem to have any affect, so I put it back where it was. Only codes were 31 & 23, which I believe are normal.

Edit: I just double checked, and I think I was turning the wrong screw for idle speed (left). So the info about having no effect is probably incorrect.

 

My '85 Turbo was hard to start, smelled rich and ran poorly until warmed up AND got poor mileage UNTIL I found a loose MAF conection after the MAF. Fixed that and it's been doing much better.

Check for leaks. Cracks in boots can be hidden on the other side.