Yamaha V6 200 OX66 SSII will not go over 4,000 RPMs

[hankandgina]

I have a 2004 Yamaha V6 200 OX66 Saltwater series II. I can push the throttle up to ~3700rpms and then use trim to get to 4,000rpms. The throttle lever goes about 95% to the top to get to 3700rpms, if I push the throttle all the way forward (100%) the rpms actually decrease to around 3200rpms. It is very difficult to get into neutral or reverse. Reading other posts, rpms sound like a fuel related issue, but what confuses me is the difficulty of getting the throttle to transition smoothly from forward to reverse and neutral. And also the rpms decreasing when the throttle is fully pushed forward. I can pull the throttle back about 1" to about 95% and the rpms increase again. I have a video from my iPhone I took. Can I post that here for analysis? I have changed the water/fuel separator, the spark plugs and the fuel line from the water/fuel separator to the primer bulb. I have to use ethanol gas due to no place near me selling non-ethanol gas. However I have always put in stabilizer when I fill up. The boat was ran about three times a month before this problem. On the outing when this occurred my engine was running normally for about 15 minutes at ~4300-4500rpms, then it immediately dropped to ~2300 rpms. My first thought was the oil level. But I had just put a gallon of oil in it and the reservoir was full, and oil system was fine. No alarm went off to indicate an oil problem. The engine compression is consistent throughout all cylinders. Less than 10 psi difference between all cylinders. Any more detail I need to provide please let me know so I can help you help me.

Thank you very much for any advice, suggestions.