Carrier 48SS cuts off when really cold out (internal control fault)

I have a Carrier model 48SS018-060. It got down to 16 degrees F the night it went out. I have the manual so I did the \"reset\" procedure and it worked fine for 4 days and cut off again, LED is flashing 8 times = internal control fault according to the manual. I just reset it again and it looks like we are not going below 33 degrees here (hopefully for the rest of this season). The fan does NOT blow cold air when it goes out. The orange ignitor wire was touching the yellow flame sensor wire so I took care of that with a quick reroute. The guy who came out last year when my mom lived here told her that the burner was rusting and would need replacing soon. Of course that is what he told a woman so I take that with a grain of salt. It didn't look rusted to me but I didn't remove it and look inside of it. I did take some pics I could link to.

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Some pics:

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Do you have any supply registers closed, like closing off a room? I ran into a problem with a Carrier unit once that was tripping a high limit safety because it wasn't getting full airflow. The warmer the outside temperature was, the quicker the unit would shut down.

TDD