Tried search.
Here´s the deal.
Stock 90 RS.

Runs like a champ.
Just performed total tune up.Fuel filter,ign components asf.
Also upped timing a bit.
Original prob was with rough running-especially so at idle.

Prob was accumulated,but major flaw was traced to O2.
Replace that one too.(In fact three times)
Have run Win ALDL-and the prob is that it checks fine-at least as far as i can gather.

Now..
What happends is that as you get to a standstill the idle Q is just fine for 15 secs or so.
After that it´ll develop an intermittent miss and finally die-ONLY IF O2 IS CONNECTED.O2 output has been checked both from the sensor direct and the ECU.No probs what so ever under load or power.
As long as you let her rip in OL mode she´ll stay steady at 0,3%CO and approx 70ppm HC,but as soon as you put her in CL mode those figures will trap to 7% and 700ppm respectively!

As is car is run,and runs absolutely like a charm,with O2 disconnected.
What am i missing here?

 

This sounds similar to what mine is doing, but my O2 sensor makes no difference connected or not. The only thing that keeps mine from stalling at idle once it's warmed up is disconnecting the service connector. But no advance is no fun

 

Your coil could be going south. I would check that. You could also have clogging injectors. Both of these things would allow your car to run okay under load but when you idle it can make your car miss.

 

does the car run better with the air or defrost turned on? If so the fix is to take out your IAC sensor clean it very good and re-install. You could replace it but I have cleaned mine numerous times and it worked like a champ (saved $30).