Warm starting/choke problem

[TimQ]

First the requisite details: 86 c10 4.3 v6 automatic with 90k original miles, rebuilt 4-barrel quadrajet put on last year with electric choke. Truck otherwise runs good.

I've had a warm engine starting problem crop up in recent weeks that I seem to have narrowed down to a problem with my choke.

If I drive till the engine is good and warm, then park the truck, wait maybe 20 minutes or so and come back sometimes it just won't start. When the problem happens, it turns over just fine and even "fires" for just a split second and dies. After that, no amount of cranking will do.

Last night I got it to happen in the driveway. I looked at the carb and noticed the choke was closed completely. I had my wife crank it while I held the choke open and she fired right up. Just for kicks, I repeated the process a few times (e.g. waiting 15-20 minutes before a restart) and it wouldn't start again unless I opened the choke.

If I try to restart right away after running the engine, it's fine. But if I come back between 20 minutes and an hour or even more later it won't start because the choke is closed. Four + hours later it starts fine.

It's been really cold here lately (not really been above freezing all month) so I suspect that thiis maybe causing the choke temp sensor to cool off quicker than the engine itself. Does that make sense? If so, how can I fix it? Is it an adjustment issue or is it a faulty part?

I've tried reading some related threads here but didn't seem to find the exact same issue.

Thanks in advance,

TimQ