jenn air gas oven bake problem

Husband trying to fix oven. All burners, griddle, broiler, small oven work fine. Bake setting started taking a while to ignite, but would (with a boom). About a month ago it seemed to take longer to heat then it never got up to right temp. My husband slid it out and thought the back valve which all the gas line came out of was problem. We ordered from Appliance Parts Pro. Nice part, but not the problem. Looking further he realized that the gas coming out at the bake ignitor seems to sputter and never come on fully. We narrowed it down to possibly the thermostat, oven broil Part # AP4091094 at another $200+. I was looking at the schematic diagrams and think it could be the bake valve- which is $150+. SO, from the description of the sputtering gas, could you lead me to the correct part so we’re not buying a part we don’t need again, please:) Thank you!