Further Update on my MK2-7mgte
Installed a HAC sensor (pre 89 harness). Car has had no HAC sensor since the 7mgte conversion. Put one in and instantly got 1-2 points of vacuum at idle and cruising. I also went from 4.10 rear to 3.73. No other changes, adjustments, or maintenance. Seems closer to what the car should be. Still can't turn more than 5 lbs boost.
Another LV-LA Road trip MPG report:
outbound 3200 rpm 90 MPH cruise 23.1 mpg
return 2500 rpm 72 MPH cruise 24.2
No A/C operation
Next Local 200 mile operation 19.8 MPG
Much satisfying improvement. The next thing to check is the ISC and CSI. There have been some small operating variances that suggest that they should be cleaned and checked. Will also be doing a Manual boost controller to check on the limited boost.