My husband just replaced the ignitor on my 9 year-old GE XL44 gas stove b/c it wouldn’t preheat to the correct temp and it didn’t heat to the correct temp at all (I would have to set it 25-30 degrees higher than the actual temp to get it to the temp I wanted).
Even after changing the ignitor, the temp is off by about 100 degrees when the preheat button "beeps". It will get to the correct temp eventually and it seems to be maintaining the correct temp (so far anyway) as long as it’s not set too high. The higher I set it, the more difficutly it is having getting to and maintaining that temp (ex: 350 is fine, but 450 not so much).
I’m really hoping that the thermostat doesn’t need replaced, but I want to make sure my oven is working properly before Thanksgiving. 
Any ideas?
Thanks for your help!