Gas Jenn-Air oven will not heat up?

My burners on the top all work fine but the broiler only works some of the time and the oven does not turn on at the bottom burner. I opened it and checked the top (broiler) and bottom (bake) ignitor. They each get red hot but the gas/propane never gets expelled to light on the bottom and only works some of the time on the top. The oven was purchased in June of 2003.

How long has this been going on??

For a week now