Get some propane or carb cleaner, start the engine then carefully spray around each of the throttle body rubber manifolds descending from the air box—one-at-a-time. Spray the z-tube that runs from the crankcase to the air box also and verify its condition. If there's a change in the revs when sprayed, the component is leaking. These are simple measures to determine common problems. If the air flow meter is plugged in, leave it alone for now.
