Curious thing seems to be going on with the fueling system on my VFR. For a few weeks now it's been running on the rough side, with a lumpy idle where the tach jiggles up and down a hundred rpm up and down. However when I run a full tank of gas with Seafoam in it she runs smooth as glass by comparison, and sounds and feels smoother through the whole rev range. Since I've owned this bike I've run nothing but Chevron 91. Anyone have any thoughts?