More than likely, you have a bad igniter on the bake manifold in the oven. As the igniters age from repeated use, they can become weak and longer function properly. Just because they glow, does not mean they are good. If you are experiencing ignition problems, the following link explains a little theory about how these igniters work and how to replace one:
http://www.fixya.com/support/r3575727-replacing_an_oven_igniter_on_a_gas_rangeThe burner manifolds in the oven each use a glow bar or electrode type igniter with a gas safety valve to ignite. Both oven manifolds are controlled by the Electronic Oven Control (EOC) board, which is your clock/timer on the control panel. If the surface burners work, but the oven does not, the problem is usually not a gas related issue. Since the broiler still works, its more than likely not a control board issue, either.
Replacement parts (if required) can be purchased at any of the following websites:
searspartsdirect.com
pcappliancerepair.com
appliancepartspros.com
repairclinic.com
Prices vary between these sites, so shop and compare. The first three sites listed also offer helpful exploded view diagrams to help you locate and properly identify the parts you need. The part number for a replacement igniter for the model you have listed is 5303935066. The price is about $23.
NOTE: It is common for the BAKE igniter to require replacement more often than the broiler, due to the frequency of use.
If you have any questions please post back and let me know. I hope this helps you.