hi, I have a 1988/89 xjs 3.6, I am having trouble , the computer read out on the dash tell me there is a fuel failer,turn the key off then back on (this imfo is in the glovebox book) then it reads ff3 what does this means, the car is running fine,except when you are driving and back off it takes a while to respond (eg no engine braking till it idle down).