Ron, I might suggest that you start by verifying that the lp gas pressure is correct at 11" water colum under working load. If too high this could supply more BTU's than the refrigerator was designed to operate properly. The next would be proper air flow. Are the fans coming on; they probably are if it woks good in electric mode and it is hot outside. The next thing to check would be the burner itself. Be sure no rust flakes have fallen onto the burner distorting the flame; it should go straigh up the chimney flue. Good luck and keep us posted on the diagnosis.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7