Maytag MER5775QAS

Question

My oven is not heating up correctly. Last night when I went to cook I set the temperature to 350 but 2 hours later it was only at 305. When I opened the door to see if it was really 350 the oven was warm but I think the display was correct and it was about 305. After that the display read 250 and 2 hours later it only up to 255. The oven is getting hot but only to 250 even if I set it for 400. Any ideas?