...
CoordinateDeviationFromTarget = 150; -- change this number
 
function CastHeal(skillc,tar)
	if (skillc ~= nil) and (tar ~= nil) then
		if (tar:GetDistance() > 600) and (tar:GetDistance() < 4000) then
			loc = tar:GetLocation();
                -- I changed the below code a little bit
			lX = loc.X + 150 + math.random(-CoordinateDeviationFromTarget, CoordinateDeviationFromTarget);
			lY = loc.Y + 150 + math.random(-CoordinateDeviationFromTarget, CoordinateDeviationFromTarget);
			MoveToNoWait(lX, lY, loc.Z);
...
...
	if (IsPaused() == false) and (GetTarget() ~= nil) 
     and not (GetTarget():IsAlikeDeath()) and (GetTarget():GetDistance() < 8000) 
     and (GetTarget():GetDistance() > 600) and (MoveStamp + 4000 < GetTime()) then
	   loc =  GetTarget():GetLocation();
         -- I changed the below code a little bit
	   lX = loc.X + 150 + math.random(-150, 150);  -- change these numbers
	   lY = loc.Y + 150 + math.random(-150, 150); -- change these numbers
	   MoveToNoWait(lX, lY, loc.Z);
	   MoveStamp = GetTime();
	end;
...