What I meant by low vacuum:
At idle, out of gear, economy gauge is at maximum.
At idle, in gear, economy guage is at the middle.
accelerating, economy guage is pinned at minimum.

When I disconnected the EHA, the economy guage showed better readings, but was still not running as good as before it started running bad.

I thought of the O2 sensor as the culprit, but I disconnected the wire to the EHA. I would think this would eliminate the O2 sensor from the equation, and the EHA would also then not add any fuel.

The EHA adjustment sounds promising, but why would it go out of adjustment so rapidly?

Thanks,
Phil