[Black Raider]

Попробуйте так:

Код:

var i, j, allchar : integer;
    st : string;
begin
  allchar := 0;
  for i := 0 to RichEdit1.Lines.Count-1 do
  begin
    st := RichEdit1.Lines[i];
    if   (pos('G',st) > 0)
      or (pos('M',st) > 0)
      or (pos('F',st) > 0)
      or (pos('X',st) > 0)
      or (pos('Y',st) > 0) then begin
        for j := 1 to length(st) do
        begin
          if (st[j] = 'G') or (st[j] = 'M') or (st[j] = 'F') then
          ColorText(RichEdit1,allchar + j,clGreen);
          if (st[j] = 'X') or (st[j] = 'Y') then
          ColorText(RichEdit1,allchar + j,clRed);
        end;
    end
    allchar := allchar + st;
  end;
end;