Cold Start Problems on 22R 2.4 Engine

I have a 1982 Toyota Pickup w/ the 22R motor. Engine will start up easily cold or hot, but must warm up before it will idle smoothly and on its own w/o dying. Is there a tempurature sensor of some type on this truck? it is a very consistant problem and goes away immediately once the tempurature is at normal operating level. Have checked EGR valve, it had a lot of carbon built up at the opening that meets the header but i got it out, this truck is also equipped with an automatic choke and i have a suspicion my problem could be located there because the engine will idle fine on a cold start if you manually choke it from under the hood, could be something as simple as that. If anyone has advice on my problem i would greatly appreciate it the mechanics in my area haven't offered any help. thanks -matthew