1989 DT75 Will not plane.

Have a 1989 DT75 on my skeeter 16' boat and cant get enough rpms to plane out. Here is what I have done:
1. Changed Impellar
2. Changed Lower Unit oil
3. tore down and cleaned carbs
4. changed out all fuel lines
5. installed new bulb
6. installed new plugs
7. check throttle sensor .52 on low end and 2.97 on high end
8. new fuel diaghram

idles real good and runs well on the muffs. Get it in the water and it still runs good but doesnt get enough rpm to bring the boat up on plane. Have adjusted air needles and even oil mixture but nothing. Was wondering what my next step is. I heard there might be sensor that doesnt allow it to kick out the rpms. When in the water my water alarm beeps for a few seconds until water is pulled up into the motor head. I am stuck and need some new advise since no mechanics in Idaho will work on it, so I am off on my own. Thank you for the advise.

I am new to this forum but here it goes, did it run before or it this a new setup? what I am getting to do you have a prop with the right pitch? lower pitch more rpms.

First Check your spark and compression,Spark should be a blue looking fire.make sure you have spark on all cylinders.Could be a bad coil,spark plug wires,check your timing.let me know!!