Slithering noise under my 96 Coupe

Thanks to all who have helped me in the past.

Now "old reliable" has developed a noise in front that can only be
described as "slithering metal" when I doing a steady 40-50mph with a
light touch on the throttle.. Not rattllng, clanking or grinding...its
slithering...almost like sucking the last bit of soda out a can with a
straw.

No decrease in gas mileage or performance. It does not make the noise
when in neutral or park no matter how I fiddle with the gas pedal. Only
at steady speed with partial throttle.

Any guesses?

Also...if its a transmission problem that my local mechanic cant
diagnose/fix, do I have any other choices than going back to the Honda
Stealer?

Thanks in advance.

-Slim