I did a test drive of the Bronco today and was getting single digit MPG. Because of the whole snow and no garage thing I tried to take it to the mechanic. Due to high demand he's only taking non-running cars right now. Hew suggested that I see if the choke is stuck and come back in about five days if I can't get things figured out.
The choke isn't exactly stuck, but it sure isn't opening. If I push it open manually it rebounds to where it was as soon as I remove pressure. Since the choke is opened by a bimetal spring, to me at least this means that it just isn't getting hot enough.
Apparently converting to a manual choke is an option, but I haven't found the details on doing so just yet. It may be easier.