Perhaps your regulator is limiting the flow. Turn off the gas at the cylinder and the regulator. Slowly turn the gas on and off two or three times. Then slowly turn the regulator on and off in the same manner.
To start the fryer: With both valves off, turn the cylinder valve all the way on. Next slowly turn on the regulator.
This should reset the flow meter in the regulator and the OPD valve in your cylinder.
If this doesn't work. Disassemble your burner and make sure there aren't any obstructions. I had to file down a few spots on a King Kooker fryer due to poor castings.
Good luck.