My sister in law put six defrosted chicken thighs into one of those throwaway aluminum pans, poured a can of Cream of Celery soup over them. Covered them with foil and put them into a 350º oven. After 45 minutes, she uncovered them. It took another hour and 15 minutes, a total of two hours before they were done. She also said that the pork roast she did on New Year's day took a long longer than it should have by using the weight/temperature guideline. And in the past, other items put into the oven seemed to sometimes not be done when they should have been. I had given her one of those probe thermometers, the one where the probe goes into the meat and the thermometer sits on the counter. She told me that she forgot to use it on the pork, but her husband used it to check the oven temperature. I didn't think this type thermometer would give an accurate reading of the air temperature, I still think the thermostat is wrong. But, she said that she baked a cake, and it baked perfectly in the time and temperature that was on the box. Any ideas of what the problem could be?