I have a 2000 Centurion Elite with the 350 Mag MPI ski motor .For 7 years now I have had a problem that occurs after running hard for 1-2 hours .The boat will not start after shut down .It will turnover and then run and sputter for 15 to 30 seconds and sometimes backfires .If allowed to sit and cool for 30-60 minutes it will start and run fine.It always runs great and starts on the first turn every morning and at the beginning of every season.I have had it to 5 different shops and they can never get it to happen when they run the boat.I have replaced the entire cool fuel system,pressure checked the gas pump 3-4 times,drained the fuel system,changed the cap and rotor,changed the temp sensor near the thermostat,changed the alternator,and done all regular maintenance .i have 206 hours on this boat and this started around the 100 hour mark.The boat is kept and used exclusively at 6200 feet in elevation and I have wondered if that matters.
any help would be appreciated