Here's one I can't figure out. 2003 FX140. New Solas Impeller and solid stainless wear ring recently installed. Had a few good sessions on it but now after an hour the ski power gets worse and worse so that I have to limp back to the harbor at under 10mph. It feels like cavitatation and lots of bubbles blowing out the back. Checked pump area and everything looks sound. Pulled the impeller out again and the rear bearing seems fine. Motor mounts are good. Took it out again and same problem. Only telltale is the edges of the impeller look like they are rubbing against the wear ring as they are slightly flattened but when I shine a light through the intake there is nice clearance all the way around. I'm thinking where the impeller shaft goes into the engine something in the drive line is work out causing the drive shaft to spin out of round. Any way to check this?

Any help would be appreciated.