[chrismorse]

Well, this is a fairly embarrassing mistake I made on my 308, that is directly applicable to most cars, including our Porsches.
I overhauled the Webers and was "cleaning up" the engine compartment, replacing the hoses, temporarily removing the evaporative and emission stuff, trying to get the carbs dialed in. I then left for my first Ferrari club event. 200 miles down the road, All fine, car ran great, until I was climbing the road before the descent to the Golden Gate and the car started to slow, seemingly running out of gas, ease up on the throttle, car picks back up.
So, I ended up missing my first Ferrari event to do a roadside fuel pump replacement, which didn't fix the problem. Cracking the fuel tank cap and hearing a big hiss, was a humbling A-HA moment - I had hosed myself by cutting off the fuel tank venting, choking off the fuel tanks admission of make up air for fuel used.
FUG
So, my friends, you must maintain fuel tank venting.

Chris