i have a 48 Hp Evinrude that up to last night ran good. While I was running wide open all of a sudden it just started slowing down like I was backing off the throtle. It didn't stall out on me but it would only run 6-7 MPH. I can put it in reverse and it will rev up and I can put it in neutral and use the gas bar and it will rev up. It seems like the RPMs are not getting up to speed while it is in forward. It was dark when we got off the water so I couldn't really check it out. We did check the prop and it seemd ok. It does not have a tach on the motor. After we trailered the boat I put the motor in forward and could turn the prop by hand. Any suggestions to try to at least narrow down the problem?