Gas fireplace shuts off after a few minutes
Similar issue with an Escape 42DV. Different in that the flame goes out and re-ignites immediately.  

Initially, the flame would go out and come back on as if someone switched it off and then back on really quickly.  Then, the problem worsened.  Finally, the fire would go out (along with the pilot) and stay out until the system was turned off (powered) and then turned back on.

I proceeded to replace the thermocouple and the controller.  Same issue.  It wasn't until I replaced the Dexen IPI electronic ignition control module that the fireplace returned to being somewhat stable. 

I'm still having periodic shut-off/start-up within a second or two.  But, it can't be the electronics, since they're all new.  Also, I relocated them away from the firebox, so they'd stay cooler (thinking they themselves may be getting overheated); and there are no ancillary sensors.  This is a Direct Vent fireplace, where the flue is a jacketed pipe, pulling cool air in from the outside by pushing hot out the center pipe (creating a vacuum).  There is no fan in the flue.

The only thing left is to have the flue cleaned.  It is possible that there is a build up (after 11 years) of soot that is affecting the airflow, choking the fire momentarily, and the flue needs to be cleaned.

Hope my experience helps.