The Briggs Model 9 uses the MAGNEMATIC magneto. The coil on this mag. can go bad sitting. Coil P/N 290880 no longer available from Briggs. When the coil is bad, the engine will run OK at idle/low RPM. AS you throttle the engine up it will start to run poorly. You will think you have a carb problem but the true problem is a bad coil. If you look around the web you can find my coil conversion for this engine. The Files section of the Briggs group on YAHOO is one place. You must join the group to access the files section.