I have the same symptom. After getting fuel in SC my Passat began hesitating at speed. Stopped for a Lucas upper cylinder lubricant and injector cleaner. Car had difficulty starting! Continued driving, hesitation continued but diminished over next two hours. Did not stop engine til home in Fl. No further hesitation but warm starting became evident. Car cranks for 15+ sec B4 starting. (Alternatively turning ignition off for 5+ seconds then cranking again it starts right up!). I’m inclined to think the bubbles may be the issue.
BTW I changed the fuel filter (dirty & sediment in housing)!
BTW I changed the fuel filter (dirty & sediment in housing)!