Have been having a cold start running problems with my 86 GL....some
stalling in warm, damp weather and engine racing (2000 RPM) in cold weather.
Removed the throttle housing from the intake air distributor (remove intake
air hose....plus 2 screws--see Bentley p 24.47) then cleaned some crud off
the cam under the housing which moves the throttle switch, and added a touch
of white lithium grease.   Seems to have cured the problems. This cam/switch
arm area is not sealed [though the switch is], so likely I am not the only
one to pick up some dirt.   

Would recommend checking this area if you have starting or idling
problems---the throttle switch has to be at continuity at startup to send
the right signal to the computer.  Also the gap has to be set right so the
switch opens at the right time under acceleration......(see Bentley
24.58-59).  And you also can clean up the throttle plate and shaft easily
while it's removed....mine was dirty.   

This is a cheap and quick check.  You might want to order a replacement
gasket (025-133-073....$2 from Camelback VW in Phoenix mailorder)
beforehand.  I hadn't and needed a good shot of silicon to patch up the
original to hold until the replaement arrived....then had to take it apart
again.

                                             John Foster