Just had engine rebuilt and installed in my 90 Jetta GLI 16v. Engine will not start unless throttle is fully opened up. Engine will misfire and run poorly unless vacuum line is removed from back of intake. When it is removed, it runs balls to the wall. If you cover hole half way, engine runs much better. Any help would be greatly appreciated!
Which port on your throttlebody or (intake) A picture goes a long way.
Is it the port for the Fuel pressure regulator on a Digifant?... Do you have Digi, or CIS?
VW's don't like Vacuum leaks or unmetered air at all. So there is a different issue than what you are thinking.
If it is the FPR port, then you may have the FPR hooked wrong or it is bad. Is the Throttle body bypass screw o-ring good? Is you throttle body switch set correctly?
What do Divorces, Great Coffee and Cars all have in common?
They all Start with good GROUNDS.
Replace all of them that you can, 99 percent of flakiness will disappear.
92, 93 Cabriolet.... 89, and 90 are Deceased.