Really weird ignition issue...

I beleive the reluctor wheel alignment can be changed by flipping (editted to add: no it can't) it or engaging the other slot in the reluctor. I forget all the details now, but the first dist I pulled apart took a lot of trial and error to get back together correctly.
I have also seen the reluctor gap change with vacumm applied. Worth 5 minutes with some feeler gauges and the mightyvac to look into.
Also, I believe you can get a rebuild kit for the mityvac. The rubber guts are probably turning to dust and causing the erratic behavior.