Before and after replacing the O2 sensor, the following faults codes would
be captured with just a few minutes of driving:  231 (long-term fuel trim,
part load)  511 (long-term idle air trim)  512 (short-term fuel trim).  I've
been fussing with these codes for many weeks and miles.  The engine has been
running a little rich so I suspected faulty O2 sensor.  The new one did not
affect the problem.  Then I suspected an air leak and fixed one of those.
It idled a tad smoother.  Still the fault codes would keep appearing.  This
past attempt, the codes were cleared, plugs inspected (newish 4 prong Bosch
platinums) and the compression checked (roughly even 160 lbs).  It was at
this point the engine would barely idle for a few seconds and has since
ceased to fire.  I have voltage on all six coils.  All are in their correct
places.  I see spark on #1 and smell gas in #1.  I hear the fuel pump when
turning the key to the run position.  I've tried resetting the fuel trims to
the default by disconnecting the battery for 10 minutes.  That did not help
either.  I hate to jump to the conclusion that the ECM or MAF sensor is
damaged.  I was hoping someone would recognize these symptoms and point me
toward the guilty component.

Thanks,
Ric