Every winter I run into the same cold starting problem with my 84 305- I pump the gas once to engage the choke. I'll start the truck and she'll fire right up. After about 10 seconds at half-assed high idle, the engine will stall out with syptoms of rich mixture. I turn the key again right after she stalls, and the engine will fire right up to high idle with no problem at all. This happens EVERY morning, but I just learned to live with it. BTW, the truck runs perfectly other than this. What is causing this problem?