Cranks but won't start, strong gas smell
 

I have a 2008 Mini Cooper Clubman S with 38k miles. It suddenly won't start. It cranks and almost catches but it won't start and now there is a strong gas smell like it is flooded. Before this I was having trouble with it dying after first start up after sitting overnight or after not driving it for awhile. It would idle rough at first start up then die. Then it would start on second try and idle rough for the first 5 minutes and then start running smooth and then start fine and run smooth the rest of the day. I had a check engine light on when this was happening. I put a bottle of Techron in my tank and filled it with Shell V power and that seemed to solve it. The CEL went out and it was starting normal and running fine. I filled it with Costco gas and the next day it started, died and then wouldn't start and smelled like gas like it was flooded. It hasn't started since and it just cranks, almost catches and smells of gas. There is now a gas smell on the oil dipstick. I don't know if the Costco gas was bad or what is wrong.