'94 850 sedan non-turbo, 205K miles:

Had intermittent stalling, random, sometimes at startup, sometimes
after engine hot.  Seemed worse on hot days, or in heavy hot highway
stop+go traffic. Worse also when a/c has been running, seemingly. Up to
now would restart after sitting off for 5 min.

My trusty mechanic has, in the following order: replaced fuel filter,
fuel pump, fuel switch relay, two fuel injectors that appeared clogged.
We are both scratching our heads.  I tried to loosen my gas cap per
suggestion on this board, but today (mid-90s), on my way to work it
just stalled, and even after sitting for an hour, would only turn over
and over, almost, but never starting...

Any suggestions?