Abineefelligh

My name is Dan. I am new to this forum. I am having problems with my motor. I had to change the starter on it this year. Once it was changed it took forever to get it to start. I got it started and took it to the lake. Once in the water it would not run but about maybe 5 mph. I had to throttle it up carefully or it would die. I read on this forum of things to check. I have checked my compression. All four cylinders are running at 60. I have good spark on all plugs. The motor will not miss or cut out when I cover one of the carbs. I am just wondering what is up I cannot afford to put it in the shop. A mechanic said I needed to rebuild the carbs. It does not sputter, bog or anything when hooked up to the muffs. Just in the water. Any suggestions?