Welder for body work?

I have a 110 stinger I bought from Eagles hardware ( that tells you how old it is )but it has been great for general use. I have found that .030/35 flux core is too heavy for sheet metal . I'm not a great welder so I have trouble controlling heat . Too low and it sputters , too hot and it flashes. I think gas would be a good up grade.
Have you tried dialing in your wire speed along with the heat?