87 5KCSTQ and 2312 code

[MHLIGGINS@aol.com]

    The black car started running poorly this week. Very poorly. Got home 
from Murfreesboro VERY late Monday, had trouble on the way home. It quit 
completely, finally restarted after I pulled the wires off the coil and 
cleaned the terminals. Tuesday morning it started OK, but as I got closer to 
the interstate it started acting up again. Came home for tools...
    First code was for the O2 sensor, which was taken care of. Second code 
was for the temp sensor. I changed the "multi function" sensor and the little 
ones on the thermostat housing. Code has not gone away. What sensor does 2312 
refer to?
    Also, the car is not idling well, the Check Engine light flickers when 
the throttle is pressed. At idle it acts like there is a small vacuum leak, 
but I can't find it. It stumbles more but still runs when the dip stick is 
pulled, when the oil fill cap is pulled the engine does die.
    I notice that when the car is idling it is difficult to pull the codes. 
Sometimes I would get the 2-3, then the engine would stumble and the rest of 
the code never came through. This happened several times.
    If you have any insight on any of the above please let me know.

    Later.
    --ml