OK, hopefully a good ending to a long, frustrating battle.
I started looking for air leaks post-MAF on a hunch and found a big one. The bulb on the underside of the air intake tube had busted years ago, so I broke it off and 'sealed it' up. Well, my 'patch' was leaking air pretty bad, I guess due to several Texas summers. Resealed and my power has been restored, no ping, no codes, no timing-retard......happy Rover again.
Now that that party is over, got to get my 3 friends to go home too!