Ruben,

Do you own a voltmeter? Check the oven safety valve for continuity. Open=bad, closed=good. While you're in there, get all the numbers off the old valve and post them here.

Igniters fail much more often than safety valves. I don't want to include any "statistics" here :), I haven't been really keeping track, but it feels like you'd replace at least a hundred igniters before you get to a failed safety valve.

You can properly check the oven igniter with a meter by measuring amps. The safety valve clearly states how many amps. But most people do not own a good amp meter or a multimeter and/or don't know how to use it. So to make this repair as painless as possible (if not 100% accurate), and based on what symptoms they give me, I would usually recommend replacing the oven igniter. Works in most cases, unfortunately not in yours.