1997 Lincoln Continental Cyl 5 miss. Bank 2 lean

Had a miss develop. Code Reader identified cylinder 5 -which is in bank 2- and indicated bank 2 is running lean.
Have not been able to get rid of it. The check engine light starts blinking with 3 miles of a reset and when later checked only shows the same 2 codes. Here is what we have tried:

I first tried pulling plugs and checking gaps. -No issues found.
A test of the plug wire indicated it may be the problem so it was replaced. -Was better but not solved.
Swapped the 2 coil packs. No change.
Replaced the fuel injector- got better but eventually returned to pre replacement in gear idle shudder.
Cleaned the mass airflow sensor.
Visually checked for possible vacuum leaks.

Anyone have any other ideas?