97 Sebring cranks over but wont start

97 Chrysler Sebring LXi 2.5L V6 cranks but wont start. Started out as an intermitant problem but got worse and worse. No apparent pattern, hot or cold. It has a recent tuneup. I replaced the crank sensor, o2 sensors, the distributor, cap and rotor, and engine computer. Originally when symptoms appeared it coded random misfire and o2 sensors. No codes now but still doesn't start reliably. When it does start runs good and doesn't die but am afraid to shut off because it probably wont start again. Any thoughts or other things to check would be appreciated.

:banghead: