Shakes @ idle in D or R

[farmerfred]

I'm all but convinced that it's the valve guides now. I found a very helpful vacuum gauge site http://www.secondchancegarage.com/public/186.cfm. They describe my situation (scenario 8), including the fact that the vac. gauge needle becomes more steady as the RPMs increase. Other things I did:

• I checked for vacuum leaks but couldn't find any.
• Checked for bubbles in radiator, but found none. (I did this just to rule out a blown head gasket).
• I set the idle accounting to the sticker (600 RPM in neutral), but that became 400RPM in drive. So I set the idle for 600 RPM in drive, which became 900 RPM in neutral. The vacuum fluctuated rapidly from 7-10 in. Hg @ 600 RPM, 12-18 in. Hg. @ 900 RPM, and 18-20 in Hg. @ 2000 RPM.
• I set the carb idle mixture by vacuum instead of tach., and that sure helped.

I'm hoping to do a compression test tomorrow.