Sometimes the Acceleration Enrichment (AE) which is similar to a carburetor "Pump Shot" needs adjustment to correct for an unidentified stumble.

My method to adjust AE is with a Wide Band Oxygen Sensor (WBO2). Ideally the Air Fuel Ration (AFR) during AE would be between 12.5 - 13.5.

Without a WBO2, its a "Best Guess" if an unidentified stumble is an AFR being Rich / Lean AE fuel table.

Then again it could be spark advance causing an unidentified stumble. Having a WBO2 helps identify if its a fuel table or spark table causing an unidentified stumble.

dave w