[STYLUS]

Starting problem is still in limbo, but with a few more clues. Took boxster to napa today to be diagnosed . Would not restart at shop but code po102 showed mass air flow circuit low input. Recommended to replace mass air flow sensor and/or crank angle sensor. After an hour was able to restart engine but was hard to keep it running (not cooled enough for a sure start) heard misfiring and ran high rpm to keep it running. On the road home, ran fine, no misfire, but noticed a gas smell at stop light. After parking at home, tried to restart and restarted perfect. Fifteen min later, will not start!
Removed underside plastic to replace water pump 3 wks ago and did not replace damaged panel? One thought that fuel lines are overheating. Next, replace crank sensor or air flow sensor. With clues, i would guess airflow first. ALSO, previous records 08/08 indicated fault codes indicated 02 sensor cyl 4-6, 02 range cyl 1-3. recommended replacement of forward oxy sensors. where to start?