Hello. I have a vented gas log set that I'm having problems with (It's the Texas Bonfire model). I can get it to start usually by lighting the pilot, holding down the knob for about one to two minutes, then letting the knob up and turning it on. At that point it burns nicely for about 2 hours - and then goes out suddenly. Also, at times, I'm unable to even get the pilot to stay on even though I'll hold the knob down for about five minutes. I've replaced the thermocoupler a few times. Not sure why it keeps going out. I've also lit the pilot and let it go without turning the set on - just to see how long it will stay lit - it always goes out after several hours. I read something earlier that some models have a second sensor that will turn the unit off it gets too hot? It's driving me nuts! Any thoughts on what it might be? Thanks much in advance for any replies.