My GE profile gas oven takes for ever to preheat especially when you are trying to cook at 400 or above. I took the drip protector off and turned it on and the burner does light but the flame looks weak.
When an ignitor is weak, the gas valve will not open. I suspect you either have a malfiunctioning pressure regulator or maybe low gas pressure coming to the house. Any other gas appliances in the house? They operate ok? I had one GE where there was an obstruction in the gas line from the gas valve to the burner [weird].