77 124 Spider Calif Smog

[Robert Whitley <rwhitley@domain.elided>]

Greetings,

I've got a 77 124 Spider (1800cc) which passes the CA smog emissions test.
The timing checks out OK, but it fails the vacuum test at 3000 RPM.  I've
been told by the test technician that the EGR valve should receive vacuum
from a "thermo vacuum switch" at 3000 RPM.  Well, by his vacuum gauge, this
isn't happening, and he can't pass the car for this reason.  He's got a
reference book which says that the vacuum should be present.  

Now, a fiat mechanic who allegedly knows his stuff says that emission
control system on the car is working perfectly and that the thermo vacuum
switch should not provide vacuum to the EGR valve at 3000 RPM.  Also, the
thermo switch was just replaced and it does work OK at low RPM.

I haven't got a chilton manual handy, and since the car is now in the hands
of a prospective buyer, I'd like to fix this ASAP.  So, I'm wondering if
anybody out there can resolve this discrepancy.  Is the fiat mechanic wrong?
I'm suspicious, since I don't understand how the thermo switch would know
about RPM, that for some reason the car won't generate good vacuum at 3000
RPM like it should, but I'm not sure why that would be.  

Any suggestions appreciated, either to the list or to me privately.  Thanks.

Rob