I also had the same problem. I solved it by measuring my oven and buying a pizza stone to fit the oven floor. It helps regulate the heat and keeps the bottom of dishes from burning.
I also have a small oven thermometer that I keep inside the oven when cooking to watch the temp.
I purchased the pizza stone at Walmart. It came in a box with a metal pizza stone rack-holder (which I threw away) and a pizza cutter for $19.
I did forget to take the pizza stone out of the oven while traveling and it cracked, but it still does a great job.