1989 Buick Century Estate Wagon 125K miles 3.3L V6
About half the time per week when I start my car it will idle very rough with the check engine light on and the coolant temp warning light on. Sometimes it will die after 3 to 10 seconds of this and sometimes it will clear up and the two lights will go out. I have checked for trouble codes but I have not been able to pull any. Does anyone know what this might be. Any help would be great.

Could this be an iac problem?

Both the ECM and the temperature warning light use the same sensor (if your car has a temp guage, there will be a separate sensor for the guage too). I would check the wiring to the CTS (Coolant Temperature Sensor) first and if it checks out, I would say it's time for a new sensor.

The CTS is mounted in the intake manifold on the passenger side, and it screws in horizontally with a 2 wire oval connector.

that sensor going bad could cause it to run rough?

yes, the CTS is used by the computer to meter fuel, so it will run bad if the CTS is sending the wrong signal.

I will try that and repost thanks