1996 Ford Bronco Intermittent Stalling in Cold Weather

Engine Performance problem
1996 Ford Bronco V8 Four Wheel Drive Manual

My trustworthy (150K miles) Bronco has run poorly or stalled 3 times in the last month. Details as follows
1) Lost power on a cold (~20degF) morning after driving 6 miles after leaving a warmer (~45 degree) garage. It idled poorly for about a minute after I pulled off to the side of the road, then died. I switched off the ignition, it restarted immediately and ran beautifully for the next couple of weeks.
2) The Bronco sat outside (~15 deg F) all day while I was at work. I drove 10 miles at highway speeds and then exited onto a surface street. The truck bucked violently the rest of the way home. I shut the ignition off and then restarted the car. The truck continued the violent bucking (stalling once or twice a second followed by full power). I drove the car to the mechanic the following day. It started and ran great on the trip there. The mechanic reported the fuel pump pressure was good (38 psi KOEO, 33 psi KOER) and the wave form looked fine.
3) A week or two later the Bronco started bucking again after leaving leaving Christmas dinner (sitting 4 hours at ~20 deg. F) and then died after I pulled off the road. It started right back up and ran fine the rest of the way home.

I left it outside last night (18 deg F) to try to duplicate the problem. It started right up and ran fine all day. No trouble codes have appeared since this started happening. This is all happening in Denver where the humidity is very low.

Help! I've taken good care of the Bronco since new, use good gas, have change the fuel filter regularly (about 7000 miles since last time). I'd like to hang onto it but I need a reliable vehicle.