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Tapping @ startup + hesitation = bad lifter?

I have a 1993 90CS, with the 2.8L V6 engine. I've noticed a couple of symptoms 
and would be greatful for whatever help other list members could provide for

For the last couple of months I've noticed a slight hesitation, almost like
missing, between 2500-3000 RPM immediately after startup in the mornings.
It dissappears within 2-3 minutes of running and does not reappear unless
the car is left overnight. At first I thought this might be an ignition
or fuel-injection problem, or possibly a problem with moisture.

I now have another theory. Unfortunately, I lack the knowlege to determine
if I'm right or if this isn't even possible...

After startup in the morning, there is a light tapping noise from the
engine, which I assume is lifter noise. I know from reading this list that
some lifter noise is normal and expected on Audis. But... If I rev the
engine to 2500-3000 RPM within the first couple of minutes after startup,
the tapping grows quite loud and harsh. As the revs go over 3000 the tapping
stops. It also stops within 1-2 minutes of running time.

So, I was thinking that perhaps there was a connection between the hesitation/
missing and the (IMO) excessive lifter noise (if it is really lifter noise 
at all). Is this plausible? Is there any way for me to try and diagnose this
more before walking into a dealer and saying "I think I have a bad lifter"?

(BTW, the V6 uses hydraulic lifters.)

I would appriciate any insight others could provide for me.