Van doesn't like cold weather

My '99 van will shut down when the weather gets below zero. This usually happens when on the highway going 60 or more. I had three different shops look at it when it was cold enough but they couldn’t find anything wrong and of course they couldn’t get it to shut down. Help please

Has it stored any codes? If so, exactly what were they?

No error codes were read when we ran diagnostics. I reset everything we could. Nothing showed up as a problem.