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Hey guys I'm at a complete loss and could use some suggestions. I have a 2005 23lsv with the 383 hammerhead. Boat runs amazing and has plenty of power but after surfing for about 45 minutes it will start to sputter and pop when trying to get up to speed. If I empty the ballast and slowly cruise it will run. So far I've changed the following with all BRAND NEW parts Fuel filter twice to make sure, fuel regulator, fuel pump. 52psi on keyup, 60 psi while running. Also changed the distributor, cap, rotor, ignition module and ignition coil - set into service mode and set timing to 10°. Brand new BPR6EFS plugs gapped to 0.045, 8mm spark plugs wires, thermostat, water impeller, ECU water temp. Removed every water like and checked for blockages ~ transmission cooler had a bit of crud in there that I cleaned out. Then I checked for fault codes with a DIY LED flasher for the Mefi 4 and had a 34(low voltage map) and 81 which seems like there could be a bunch. So I changed the MAP sensor and TPS sensor. Took it out today and exact same thing - after about 45 mins of surfing it looses power and can't get to speed and just bogs. I tried removing the intake filter, leaving the engine cover open and removing the fuel fill cap to see if that helped and nothing did. Checked for codes again after and it's showing no codes... Can any one think of anything else?

I've read through a hundred hours of forum questions over the past 2 summers. Lots of problems sound similar but I've replaced all the items that solved their issues to no avail. I have owned the boat for 11 years and never had an issue until 3 years ago when we had a couple trans bolts break that were repaired. Then beginning of summer last year the engine problems began. Many new parts and 2 dealers/mechanics later and no resolution (one is a Mastercraft dealer and the other is a former Malibu dealer). Both have lots of experience with this/similar motor. Boat idles rough (started when issues started) but runs great after throttling up for 2-3 minutes until it reaches temperature (160). After about a minute it falters then loses power. RPM's surge, boat continues to move but with almost no power that continues to fade. Move to neutral and it resets. Boat runs great for about 20 seconds and all repeats. I can do the neutral reset a 100 times and it never changes. The dealers have not been able to duplicate the fail while in the shop. It went to the MC dealer 1st because he is closest to my house: they said the ECM was bad and needed to be repaired. Sent it out for repair. Boat came back and ran for about 4 hours and then failed. After 6 weeks of them not giving my boat attention I took the boat back. Then it went to the Malibu dealer that has serviced/winterized it for me the past 11 years. This is what the former Malibu dealer detailed for me; We found a bad ground last year (19') in the motor and fixed. Motor ran well after that for a couple of hours and then failed and wouldn't start/run. Then we changed the complete distributor because we had no spark. Boat would start and run but then the original power failure returned. Then we changed the distributor again because the motor had no spark again and we found the module in the distributor bad so we changed. The last time in we found the distributor module bad again and changed. Also checked all the power wires and grounds and found one of the grounds going into the ECM to be bad. Repaired but are questioning, since day 1, the ECM rebuild that the other dealer had done. When we hook either my Rinda hand held or Laptop I often can’t get a connection to ECM. Motor also doesn’t run well at idle compared to other like motors. We are at a loss. Here is what has been done, checked, replaced. ECU was sent out for a rebuild Fuel filter replaced Fuel pump replaced Fuel pressure regulator replaced Fuel injectors professionally cleaned and tested Fuel pressure is solid at 44 psi even when boat is failing. MAF replaced TPS replaced New gasket on air intake New distributor Plugs Wires Any thoughts on this would be helpful.