Ok- I think I've solved the problem.
And I hope this helps future pumpkin swapers.
Do not remove the insulator bracket from the IRS sub frame when removing the pumpkin.
Instead, remove the two cross bolts that fasten the rear of the pumpkin to the insulator, and then of course, the front two pumpkin mounting bolts. (the insulator is a factory installed datum point)
When re-installing the pumpkin, secure the rear cross bolts before tightening the front mounting bolts.
I'm sure this is probably commom sense to most of ya'll, but wasn't to me at the time.
I reinstalled the original insulator using the old wear marks on the sub frame for line up, and it now seems to me that car runs much more smoother at speed.
I really wish that there were stickies on some of the more common swaps that we do to our birds.
For example, the lower rear Lincoln LCA swap not only needs perches, but an axel pull, a special torx holding tool to achieve proper removal and then the reinstallation of front bushing torque, a unique lower front bolt removal and reinstall sequence, Lincoln shock bolts, Lincoln short outer bolts and some other stuff I'm sure I'm forgetting 'cuss my butt's numb from doing a super coupe rear sway bar swap that may have been superflous ->
-- but I'm still happy about all the things I've learned here and I'm glad I'm a member- just please, never yell at me the "DO A SEARCH!" response when I start asking questions about my DOHC swap. --Remember, there's no sticky or tech article on this swap either.