Thanks Graham! Here's the progress - not much today...

Vacuum measured at the manifold - short rubber tube at rear of engine on passenger side - before vacuum check valve on firewall - still only 10" Hg. I need to get in there and make sure the orifice is not blocked - I am pulling 15" at the distributor (but that is with different timing, because the vacuum advance is removed when I measure at distributor). Will have to play with timing, as suggested, but see below.

TPS
Feeler gauge "out" : 3 Ohms
Feeler gauge "in" 0.016" : 0.3 Ohms
Feeler gauge "in" 0.020" : 3 Ohms
Feeler gauge "in: 0.025" : open circuit
I figured this might be close enough (0.025" vs 0.016"). What do you think?

I couldn't "play" with the timing today. If you can believe it, the only 5mm Allen key that I have that is long enough to reach the distributor lock nut is not here! I have to buy another one this week.

I tried a "test"... I disconnected the vacuum line from the MAP sensor, and blocked the line from the manifold. I then pumped 18" Hg at the MAP sensor with the MityVac. Vacuum held. Then I started the car. It ran about the same - idles smoothly, but lots of black/grey smoke.

MAP Sensor
I look again - even unscrewed the MAP sensor from the fender for a perfect view. I see no sign of a 4 mm hole for an Allen key! There is a circle of resin, surrounding a cylinder with a thread on the outside, which is quite smooth on the inside. This may be the outer screw (looking at Paul Anders' website photos). But htis is at the level of the surface of the MAP body. At the bottom of the inside of the cylinder, is a small (1.5 - 2 mm) smooth hole. I see nowhere for a 4 mm Allen key. In particular, I see no "inner screw" - no visible line for a screw driver to make contact with. I am getting suspicious that something may have been done to the MAP sensor. I have tried to take a meaningful photo, but the screw is small, and hard to get a clear image of. I will try with a better camera later.

Will keep reporting as I make progress.

Thanks again for the help,
Joe