Strange Noise under mild acceleration

Okay, I got a really annoying noise that started a few months ago, but I am finally out of ideas on the cause.

Here is the info. Under mild acceleration/deceleration around 1800-2200 rpm in any forward gear (1-5), I hear what sounds like a loose air vent flap noise. If I accelerate slightly faster, or go above 2200, below 1800 the noise disappears. I don't hear it when it is out of gear, and rev it upto the problem range. Any ideas?

Jim

Probable Cause Found ?!!?!!?

Okay, after reading over a dozen threads here and on other 'stang forums, it has become readily apparent that the clutch cable is the culprit of the 'play card in the spokes' noise, that I am hearing under mild acceleration, and it is across the rpm band, despite what I thought earlier. Also when the car is cold I get a howling noise (not loud, but I can hear it) when I depress the clutch. When I am off the clutch or a the bottom the noise disappears.

From what I have read, it looks like it time to rebuild the clutch, replace the throwout bearings, pilot bearings, seals, clutch plate, and assort parts, basically rebuild the entire thing. One major concern is the problem that so many of the forum members have had with clatter from the rebuild trans. Most seem to be due to the throwout bearing quickly being eaten up. So when the bearing is replace, shouldn't the sleeve also be replaced?

Before I am going to plop $500 - $600 down to fix the clutch (it is still driveable), I would appreciate any input.

Jim