Looking at buying a new f350 super duty. Not want a diesel looking at the gas. I pull a enclosed car trailer with a race car. Will the gas pull the trailer.

 

If you want to stay with Gas,
I would consider the 250, the specs are the same with towing capacity and better with payload, yes the axles and leaf springs may be heavier on the 350 but is that something you really need.
Also if you want a Gas F350 they are hard to find at the dealers you may have to order from from the factory. I ordered my f250 and it took about 4 weeks and I got exactly what I wanted. If you need more towing capacity consider the 4.30 rear axle, that gets you 15,000 of towing capacity, that's much cheaper than going diesel.
Mark