Can I do anything to make my gas oven better?
I would suggest adding some mass to your oven but not in the form of a pizza stone but rather in the form of a 1/4inch thick piece of steel. This not only will hold the heat well but you can make killer pizza that way too. 

Also, does your oven have a broiler? If so I would say see if that can help heat it further. On some models you have independent control of the broiler and can run the oven and the broiler at the same time.