Hi, in my pre-porsche days I did a lot of "playing" with VW's of all types and shapes. I came across this a couple of times. If your car has a manual (mechanical) fuel pump, the cause is more than likely the fuel pump diaphram. Not an expensive fix, just remember to do an oil change after you do it. Hope this helps.
Also, it will probably run even better with full fuel pressure and be more economical too!
