1989 Ford Bronco Engine running rough and stalling after wa

I am using this Bronco as a plow. Yesterday I was stuck for about 15 minutes. I left the engine running as it was below zero and 35 mph winds blowing snow. After getting the Bronco out it was running rough. I made another pass and it died and would not restart. I thought it might be flooded. I waited 2 hours and went out, it started right up. Went out this morning and it started just fine, after plowing for aproximately 10 minutes it started running rough died and wouldn't restart. Waited a couple of hours and it started just fine. I went to the auto parts store and they suggested the fuel pressure reg. I found it, Though it doesn't have a vacuum line attached to it! Should this vehicle run with the vacuum line not attached. I also cannot find the hose or where it attaches.
Thanks for your help.