I suggest you try this modification. I think it will work.

Regards
Jerson

Code:
	IF ADCON0.1 = 0 THEN 
		Nvalue = ADRESH*256 + ADRESL			' read ADC result
	ELSE
		GOTO Wait10
	ENDIF
	
	ADCON0.1	= 1								' relaunch conversion
	
	Ivalue = (Ivalue*9 + Nvalue )/10			' Rolling average
	
	GOSUB Convert
	
	IF Dvalue < Mvalue THEN Mvalue = Dvalue		' Memorize Minimum
	
Wait10:

' Prepare value to be displayed