Over in the other thread, you said it goes into reverse when you hit the brake? It sounds like the nut for reverse need adjusting. Here is page 20 of the FF18 Owners manual. The items outlined are the shifter adjustments.
Item 96 is the nut for reverse speed. Back it off a round. Do not turn the bolt doing this, as it will change the forward adjustment. Just don't back it off too much or your reverse speed will suffer.