Hey guys. My 75 horse mariner starts fine and beyond 2000 rpm runs great and revs up and down with no problem. The carbs were recently rebuilt and the plugs are fairly new. After starting the motor and after it warms up I have to shift into gear slowly because the motor acts like it is going to shut off. Sometimes it actually does. It will bog down and then come back up to speed. Once I slowly get it up to @ 2000 rpms it runs perfectly. Any suggestions?