Recreational Vehicle Lpg Tank Valve/gauge problems of the 2006 Chevrolet Cobalt

I bought the car 2 years ago. I noticed that the car stalls mostly when the temp outside is around the single digits. Doesnt happen all the time, and sometimes when the temp isnt that low. Unfortunately I still have to work and I was driving to work one morning, the car stalled on and icy road and I ended up in a snow bank. The car of course started right back up like nothing was wrong and ran for a couple weeks with out a problem. I have a constant problem with the car stalling, I even had a new engine put in because I was told it would fix the problem when I couldnt start my car at all one day and had to have it towed to a shop. Not even a week after the new engine, the car began stalling again, showing up with power steering warning lights and my mph gauge went haywire. Ironically, sometime around this whole problem, the recall for the ignition switch came out.