The FEED Rate is internal to the Coaltrol, its based on how fast the temp gets satisfied. it will vary depending on demand. if you set the temp at 70, but the room temp is 65, it will keep bumping the feed rate up until until it gets closer to the room temp, it may go from 0-99 depending on demand. ON Idle and the room temp and setpoint are equal, the FR can be 0 (Zero).
if you just hit the menu button lightly once, it will go in the FSA (Fan speed auto) and hit it again and should display FR XX.
Don't change the MIN setting, you shouldn't go below 4, that will NOT effect the coal burning off the grate, its for the IDLE burn / time. If you go too low, you could have an outfire, since it may not feed enough on idle to maintain a fire.
the MAX setting will affect the burning coals off the grate when its burning high. I would move it back to around 38 to start and see what happens, if you still have burning coals, move it down to 36.
Once you get it setup, you shouldn't have to mess with it much. In the Top of the CoalTrol section on here has the V3 Features that explains the settings.V3 firmware features