2000 911 C4 Cab hard to start after fueling!

I'm hoping that someone has knowledge of this particular issue. I bought this car in 2010 with ~38K miles on it. The issue was present when I bought it but I didn't really understand that it was an issue until much later. Every time I fill up the tank the engine is hard to start. It cranks fine but requires some gas pedal to get it going... I've driven it for an hour or so, then stopped and opened the gas cap then put it back on and the engine started right away with no issues!!! I recently took it to a shop here in Salt Lake City that advertises to have excellent reputable certified Porsche Technicians and they could only tell me that there was an issue with 2 cylinders showing misfires and they reset the CPU with no issue but they couldn't figure out why this is occurring. The tech suggested that the fuel filter MIGHT:evillol: be the issue and it would cost ~$600 to replace. My dilemma is what if this IS NOT:2cents: the problem.... Any suggestions or info is definitely welcomed!!! Thanx...

Since its after you fill up I would say it probly has something to do with the evap system in the car.... More specifically the vent valve or solenoid. Have you ever tried to start the car after you fill it without putting the gas cap back on? I mean obviously don't try to drive like this but if you do try and it starts right up I'd put my bet on the vent valve/solenoid

fuel filter is not hard for DIY mounts on top of engine on the cab