Bad Oil Pump?

[dieselracer]

I was wondering how often you have heard about oil pumps going bad? Today after work I went to the store and took a much longer commute then I am used to. So on the way back to the house. I noticed the engine was getting a little louder. When I got on it It was resonating more noise then i was used to. Then a few miles later at a stop. I noticed that the engine started to rev up on me. An issue i thought I fixed a few weeks ago by adjusting the idle mixture.. I dragged the clutch to bring the idle back down.

When I went to take off from the stop. I noticed that the engine started to make a clunking noise. That same noise when you are about to stall out an engine. I slipped the clutch a little extra and once the engine revved up the noise went away. I have heard that noise before a couple times when stalling the bike when i first got it (learning). But now it was doing it on take off and have to slip the clutch extra to keep it from doing it. I thought maybe the oil was low. I stood the bike up right. Checked the oil with the engine off. It was right at the full mark. Then I decided to start the engine while stood up and see if the oil disappears. The oil did not disappear. Gave it a quick rev and the oil was still there. It was more or less still at the full mark due to the engine vibrating. IIRC the oil should disappear from the window right? What would cause the oil pump to go bad? its a 2003 with 33,000 miles on it.

Thanks