Found the problem!!!
As I mentioned earlier, I fixed the rheostat & starting issue by running a new ground wire from the "G" term on the relay to a chassis ground. The only remaining problem was that the tach would quit when I turned on the lights. Fixed the by connecting the Blk/Wh tracer to a new chassis ground as well.
Lessons learned: when I bypassed the ECM during the Ignition upgrade install; I must've disturbed a ground for the ignition along the way.
Thanks Master4th...... just like you said: "check the grounds". Truer words were never spoken!!
Woo-Hoo; I feel like I just got a pardon by the Governor!!!
Now where's my sippy-cup and the vodka bottle?