I have a 94 gt and I did a koeo test and I got code 183. Right side still rich, at leanest adaptive limit, at idle. I've searched everywhere and I cannot find what causes the code. Maybe somebody here can point me in the right direction.

 

183 (M) Fuel system was lean at idle Single, Right or Rear HO2S

Not enough fuel flow, bad intake gasket(s), bad o2, exhaust leak.

 

I find bad o2's cause a rich condition most times, but don't forget a misfire could cause the same situation which may be a fouled out plug. Realisitically there's a big handful of possibilities with this

 

swap o2's side to side and rerun koer, if code switches to other side = bad o2

 

I replaced the right side o2 sensor this am and the light came back on. I haven't done the test again. I will after work in the am