OK, this is what happened. Blew a heater hose and decided to replace them all at once whilst doing a tune-up for good measure. Removed the intake manifold to facilitate all the work. New cap/rotor/plugs, wires are about 2 years old (Bougicord) so they stayed. Didn't clean TB since a visual inspection showed no signs of crud. Flushed breather box and attached lines. Flushed IACV. R&R ALL coolant hoses except for hose below oil filter since it is only about 2 years old (all others were original). Put it all back together and drove to Florida (300 mi). At about 200 mi. I notice the engine occasionally missing at idle when stopped at a light. It worsens over time, the longer I am at idle, the worse the miss(es). It gets to the point that it continues to miss even as I accelerate, then fades away to normal operation at speed. When idling normally, I am pulling 17-18" of vacuum, it drops to 12-14" when the misses begin. Car has not actually stalled but has been close. None of this occured before my aforementioned work.

I guess my next check should be the injectors since they have never been serviced and the car has 200K (due for a flush). Is there anything obvious I am missing before I pull the injectors? Oh, I'll be checking the OBD when I get home tonight. One last thing, there does not seem to be any connection with engine temp, it does it when both hot and cold.

Here is some more info. I ran the OBD and found the same fault in both the IGN and FI modules. Bad/missing signal from coolant sensor (maybe sensor was damaged when the heater hose blew out?). I cannot erase the code so I assume it is an unfixed problem. I'll dive in later to see if I forgot to reconnect the wires but I am afraid the sensor is toasted (parboiled?). Could this be the source of my idle woes?

RJK,make sure to check the connector for the ECT sensor-I have seen several posts/FAQ items relating to the contact(s) being pushed too deep inside the plug when reinstalling it.Also make sure you did not mix up the two coolant sensor connectors-don't know if it's even possible or would cause your symptom.
Good luck! sredwine 94 940T,98 V90

You should be able to erase the code. If you still have the problem the code will return. I have never heard of a code that couldn't be erased at least on a OBD 1 code. If nothing else disconnecting the battery although that is not the best way to erase the code. I would check the connection or at least make sure there is a connection at the coolant sensor.