Sounds like you are loosing spark, have a week cylinder or getting weak spark because of bad grounds on the ignition system. Had a 1993 150 Pro V I had to replace the CDI on because of intermittent spark. Only other things I would check is: compression, the fuel lines, if throttle is going to full throttle and if the timing advance arm moving correctly.
The world will not be destroyed by those who do evil, but by those who watch them without doing anything. Remember what He has done and remember that He is not done yet!-- GOD IS GOOD