Friend of mine has a 1990 150 Pro V on a 1994 Stratos 275 XL. Has a 23 Laser 2 prop on it and is have a hard time getting out of the hole and is only getting 4800 rpms and 51 mph at top speed. The engine has been in saltwater. Compression is around 120 on all cylinders. Any suggestions on what might be wrong?