GTV6 hesitates when cold

[Vangelis Kokkevis <vangelis@aw.sgi.com>]

My 85 GTV6 (the one I bought about one month ago) does not seem willing
to rev under load when the engine is cold.  Idling is ok (although a
little rough at times) but when I engage the clutch on first gear and
try to move, she really hesitates below 2500-3000rpm.  Once she reaches
3000rpm everything is fine and the engine pulls strong...  Since I don't
like revving a cold engine, I then shift to second and get the same
problem again...  hesitation.... Once things warm up, everything works
great...  Any suggestions on where to look?  Maybe a temperature sensor
is faulty?  She has brand new plugs,  fuel filter and a recent valve
adjustment.

Thanks a lot, 

Vangelis
83 Spider Veloce
85 GTV6
Santa Barbara, CA