I have a propane ventless type stove. The pilot lights just fine but when I turn on the main burner, it will work for about 10 minutes or so, then the pilot just goes out... the main burner will continue operating until thermocouple cools then all goes out. I replaced the thermocouple by the pilot light and still does the same thing. I took the pilot assembly apart and cleaned it very well, still does the same thing. It has one more thermocouple built into the thermostat/gas valve... I believe I would have to replace the entire gas valve to change that thermocouple. I connected another stove to my line and it worked fine so I wouldn't think the regulator is bad... any suggestions?

The other item you are talking about is the oxygen depletion sensor. It could have gone bad or you might need to adjust the assembly. THIS type of work should only be attempted by someone who is authorized or trained by the manufacturer. The oxygen depletion sensor is a safety device and must be handled with care.