Break down!!

We decided to run to Walmart this morning since it was supposed to snow tomorrow. We were taking separate cars because he had to pick up dog food for his dog (plus he was on duty). We both needed to fill up, we had ran out of fuel driving around for 2 hours looking for our dogs. Diesel had gone up here so I was going to fill up in Great Falls where it is usually cheaper. I just got on the freeway (still on the on ramp) when my truck starts to sputter. I push on the gas and it won't go. I turn off my radio and listen to the truck, it is still running but the gas peddle isn't working. I pull off to the side of the road for a couple of seconds and then try to go again. Then the Truck starts to sputter again and tons of black smoke comes out of the tail pipe! Oh CRAP!!! I thought I had done something to the engine awhile back trying to start it in the negative temperatures. I sit there for a minute and it starts to idle normal. So I thought it was ok so I try to go again. Nope same thing happens. So I call James (who is still at the gas station filling up) and he pulls up behind me. He comes up and looks at the front wheels of the truck. The tires were locked in 4-wheel drive. I couldn't believe it, I had taken it out of 4-wheel drive when I left the house (it's automatic). James was worried he thought we had trashed the transmission driving so fast in 4 wheel drive. But I told him I didn't get over 20 so it shouldn't have hurt it. He gets in the truck to see if we can drive it to the next exit (5 miles away with big hills in between). That is a no go, he was only able to go a couple of feet before it started to smoke again. Well, we came up with a different solution. The fuel was gelling. We didn't have antigel additive in the truck when we filled up last and forgot to put it in when we got home. James Backed it up the on ramp and back to the gas station (100 yards away) revving it up till all the bad fuel was through the lines. We were lucky that the lines gelled, that's and easy fix since it was warm outside, and that we had found out that the truck was in 4 wheel drive. It would have damaged the truck driving on the freeway and would have been a pain to fix. Small trial big reward!!!