Dometic Fridge not cooling properly on LP mode

Thanks for tips. I drove truck/TC for over 4 hours yesterday watching Grandson's baseball game and doing errands. Checked thermostat in freezer and is was reading zero degrees. Going to pick another thermostat for fridge but everything was real cold. More ventilation while driving? Will clean the burner assembly for sure. Did a leak test on all propane connections a week ago and no apparent leaks but will leak test the regulator again.