Given good compression, in rank order I would check (with no reference
to previous suggestions, so please forgive any repetitions):

a) Fuel Pressure - invest in or borrow a gauge for the purpose. They
are invaluable diagnostic tools. NOTE: A FI pressure gauge is a
serious bit of equipment, not the typical vacuum/pressure gauge of
carburetor days. This gets you a good filter and clear supply and
return lines when complete.
b) Spark plugs, wires, distributor, cap, rotor and so forth. Leaky
wires, carbon-tracks on the distributor cap poor connections, cracked
connections, wrong gap, worn electrode(s) and so forth.
c) Coil - Nice blue spark? Is the problem heat-related? Many VW coils
had heat-failure problems.
d) Check injectors. And run a few cans of Techron through the system
on general principles anyway.
e) Timing advance. Not sure how this is managed on that model, but it
may take a timing light to verify.

My bet is fuel or spark related. Were I to place odds they would go as
follows:

Fuel Related (clogged line or injector(s): 50%
Spark/ignition related (wires, connectors, distribution): 25%
Coil: 10%
Injectors (if vehicle generally properly maintained): 10%
All others: 5%

Peter Wieck
Melrose Park, PA