Kiwi I have this identical problem with the VFR on side streets at exactly 37-38 mph (indicated, actual perhaps 33 mph). Since I did not own it new I had no perspective and assumed that it was intentionally lean for emissions requirements. Now, I am unclear on the fuel maintenance that my guys may have done, and this may have been cleaned. But before I play with the fuel map this will be the first item to look at with the upcoming maintenance. The bike is a '99 as well and was neglected, and it has similar years to your bike, so the stars are aligning here on the possibilities.