Gas oven baking problem
I have a GE gas range/oven, model #JGBP35CEA3CC that is 9 years old. The last couple of months it has been giving me problems when I try to bake cakes, pan bread (zucchini bread), etc. The breads rise on the sides next to the pan, but the center doesn't rise and actually sinks. The bread is cooked completely, it just looks funny. I don't open the oven door during baking or stomp around the kitchen. I made sure I have fresh ingredients. I checked the resistance of the oven sensor. It was 1077 ohms at room temperature. Per a local technician's advice, I set the oven at 375 F and let it cycle three times, measuring the oven temperature at each on and off point. I used a chromel/alumel thermocouple to make the measurements I then averaged the six on/off temperatures. The average was 370.85 using the temperature when the burner clicked on and off. After it clicked, the temperature continued to go up or down a few degrees, depending on whether the oven was heating or cooling. The average of these extreme temperatures was 372.4 F. The tech claimed the problem was that it's a gas oven, but I don't buy it. I am cooking at 5600 ft altitude but on the cake mix box I followed the directions for high altitude cooking. Help!