replaced the coolant sensor last night. took 2 minutes since all the crap is off top of engine. never threw a check engine. the eprom in carrier(snap in ZIF) was loose and that did a CE light. so pulled code and saw coolant sensor error. i never had choke until today! warms up so much better AND the A/F in CL is steadier. toggles closer to 14.7/1 before toggled wider on WB. amazing what a new CTS(Delco) will do.

 

Cool that it smoothed things out for you, nice cheap fix.