Recently picked up a 2012 800 RMK 2000 miles. It has a studder or miss at 4500 rpms. I had the TPS sensor tested and replaced since it was bad. The miss is still there. Runs good at idle and over 5000 rpms. Runs out at 8150 rpms at 6000 feet and 8000 rpms at 9000 feet. Told by Polaris mechanic replacing injectors would fix the issue. Anyone else experience this issue and anyone have experience with injector service companies? I do notice the miss is less noticeable if I run the fuel chip on ethanol setting even though I only run 91 octane non ethanol.