The boat is an 06 320 Sundancer with 350 mags and V-Drive. 350 hours. I thought I may have felt a vibration after running the boat last time out but not enough to dig in yet. Today was a different story. We went for a longer cruise and after about 30 mins I felt the vibration all throughout the RPMS. I actually had a weird RPM jump/slippage about 20 mins into the trip. The instance only happen for about 1 second so I was aware but everything was normal again. The fun happened when the boat all of a sudden fell of plane abruptly. We were cruising at 4000 rpms. I shut down the engines and looked for anything obvious. Couldn't see any issues. Came back up and started the engines. I immediately noticed the port engine reved high and too quickly. I tested only the port side again and the engine revs nicely but does not accelerate the boat one bit. I shut down that engine and idled back to my dock for about 2 1/2 hours. Didn't know if anyone had thoughts on what this may be? I'll be taking it to a mechanic next week for an evaluation.