Ran great last 3 years.  The only thing I did differently when winterizing it was to run the tank near empty and put Mobil One synthetic 20W-50 in it.  Opened it and got new fuel this year.  Ran great for 30 minutes at approx. 3000 rpm.  Then engine sputted and it stalled.  Replaced coil-had hairline crack between positive terminal and tower.  It ran great, died after exact same amount of time.  Drained tank, replaced fuel.  Fuel pressure is 28 and anti-siphon valve is clear.  Same thing again.  Changed map sensor and ignition sensor assembly.  Same thing again.  Would usually start again after it sat for a while but now won't start at all.  Checked coil and igniton assembly with ohm meter and they read as if they were new.  Engine serial #0L629952  When it runs, it runs perfect.  No misses, no noises.  All fluid levels are good.  All gauges are good.  Plugs, wires, and cap are all recent.  Is getting fuel.  Oil pressure is up from where it was last year(40) this year 60 or a little higher.  Any help would be greatly appreciated.  Thank you for your time.