[scottfab]

You really should rule out a primary fuel pump starting to fail. That is how mine behaved until if finally just quit. No fun getting a flat bed ride home for my baby.

The test is most disruptive but needs to be because the pressure is fine most of the time. You need to get a pressure gauge taped to the windshield mounted on a long extension such that you can see it as you drive. Note what the pressure may be doing on the stumble. Mine would sometimes set a lean code but not always.