First off something like this is best you have a QUALIFIED professional appliance tech do it and not some person so you don't burn down your own house but here are some steps....also if you hire a LEGIT appliance tech the repairs he does are insured by his company make sure to check on the company before hiring them to fix.........here's some things i do when going to a customers house........Check your ignitor with an amp clamp or do a visual inspection..........Your ignitor should be pulling 3 amps if it's ashy colored or white and/or pulling less then 3 amps probably need a new ignitor......If the ignitor checks out ok scrub the burner where the gas comes out (fuel rail in automotive terms) with a wire scrub brush or sandpaper to rid the holes of carbon deposits.......make sure your burner is sitting appropriately on the safety valve correctly. Have you switched to propane or natural gas recently at all? Most ranges are set for natural gas and need a conversion kit for propane. Check to make sure you have 120V going to the safety valve from the main board when using the bake function. If none of those work i'd suspect the safety valve as well but in all honesty i've seen this on whirlpool and other units where the poof is just natural and never goes away with brand new safety valves........