40k Later: Some of this has been touched upon, but here's how I eliminated my run-on problem. I have 10.6:1 compression and was told I would have no problem running standard [crappy] 91 Octane gas. Wrong. Leaving the car in gear and letting the clutch just enough to lower the RPM a tad does work, but it is embarrassing if I forget (sounds ugly). 100 Octane gas is available, but it is well over $4 a gallon. Tried a couple of additives that said that they would cure the problem. They lied. Then I tried
Amsoil Series 2000 Octane Boost. It worked. One bottle at fillup. I became a dealer so I could get a deal when I bought a case. You could do the same, although you might want to try a bottle first to see if it works for you. Good luck. Run-on is nasty and it is really embarrassing sounding when it happens at the filling station next to that hot babe in the Ferrari.
Rich