cold start issues on ka-t, coolant temp sensor?

[pacefarm]

i'm having a little idle problem with my ka-t when starting the car up during colder temps outside. the colder it gets, the more prevelant the problem is.

when i start the car, it idles at approx 1100-1200rpm for about a minute, very smooth with no problems. after which the afr's drop off the chart, meter displays LEAN and the car stumbles like crazy, sometimes even dies. restarting is not a problem, starts right up but stumbles for a while. it stumbles for about 3 or so minutes till the water temps increase, then the idle smooths out. if i start driving the car slowly shortly after start-up, the stock water temp gauge bounces back and forth a little. the problem goes away after about 10 minutes of driving.

i was under the assumption that during cold starts, the car would run pig rich instead of lean all the way.......

my guess would be that the coolant temp sensor is going bad, or the connection to it. i got one on the way, just wondering if anyone had similar problems, or has other ideas.

thanks!