Loss of horse power and not accelerating

I have a 1989 130hp yamaha. Running a little rough at idle. Until I push the magneto control lever back a little then sounds good. When I push to full throttle it bogs down as if it were being choked for a few seconds then goes. Takes a bit longer then usual to get up to speed. Full speed is a lot slower then normal. I have changed the plugs. They were oily. Also had a problem with the overheat alarm. So I just replaced the thermostats, cleaned the sensors and replaced poppit valve. While taking valve off I broke the bolts off. So I changed the exhaust cover and gasket. Which involved disconnecting spark wiring. All the wiring is connected and correct. Before I replaced all that I had Horse power and full speed but did have the bogging down and getting up to speed problem. Can anyone help with some advice?