Burner comes on and then chuts off as soon as the fan comes on has anyone seen this before and what can I try

I think you better call a on site professional since usually when that happens it is because the heat exchanger has a hole in it. I would rather have you be safe then try to guess what else it could be.

Sounds like it could be a bad proving switch for the indoor fan motor. When the board doesn't get a signal from the air switch, it assumes that the fan never came on. The board cuts off the gas automatically as a safety.