Folks -

Been struggling with this problem for a week now.

Cold performance is good. When car gets up to operating temperature, it runs VERY rich and stumbles at constant speed, dies at idle. This seems to happen rather suddenly. It runs fine for 5 min. then not fine. However it seems OK under moderate to hard acceleration.
First, I had DTC 1-2-1 on socket A2, MAF sensor signal. I reset the codes, cleaned the connector and this has not returned. Since then I have only had 1-1-1 on A2. I do not think it is MAF sensor since when I uplugged it at idle, the car died, i.e. it got worse. Then I replaced FPR, no joy. Next replaced rotor, distributor cap, wires, and checked resistance of coil - in spec. according to my new pocket data booklet (BTW very handy). When I replaced wires/cap/rotor I removed gapped and read all plugs and all 5 were black as coal. Removed the air baffle from the filter box - this made no difference although since I live Houston I am considering rigging the baffle into the open position so no hot air gets in. I have cleaned the throttle body but not restarted since but I really doubt that would have caused this problem. O2 sensor should throw a code, right? ECT temp. sensor same thing - should throw a code. What else is there? - I'm stumped at this point.

DG
DG