Wife says it takes forever to pre-heat. I stated asking her about it and she says she turns it on, after a long time it goes BOOM then starts to warm up. She says is smells like gas when it goes boom. Yikes. I took the bottom plate out of the oven (2 screws at the back) and a thing looks like it glows right away when you turn it on at the back, but no fire. I didn’t wait for it to go boom 
Broiler is still fine. It’s older gas, self cleaning, no knobs on the top, just buttons, 4 knobs for burner control is all. It looks really clean under the oven floor plate. What do I gotta buy sir? - Joe
replace the ignitor .sounds faulty