GTX RFI REVVING/THROTTLE issue

[Kmcmorris]

Hey all, I'm having a tough time figuring this one out. Blew an engine last year, replaced it with an SBT, while I was at it, changed the fuel pump, regulator, new rotary valve. Ski runs fine, but not past half throttle. Anything further than half throttle, it sounds like it's hitting a rev limiter, or dropping a cylinder, until I back off the throttle and it smooths out. Runs 6,900 to 7,040 RPM, that's it. Went out and bought the can doo Scan tool, it does next to nothing on an RFI, I thought maybe it was throttle position sensor. This week, did a fuel pressure test, runs a steady 55 psi plus, even under load. SIDE NOTE: when I plug in the dess key, pump comes on, pressurizes to 50 plus, then drops to zero when pump turns off, but once I crank it, pressure stays at 55. Changed out spark plugs yesterday to see if that did anything, nothing different, and plugs were both evenly tan. Ski will run fine all day as long as long as you don't go past half throttle or so. The one thing that can doo tool did say was high voltage at MPEM. Fuel injector? I've been trying to get the local marine mechanics over, no one ever really gets back to you. Any ideas?