90 hp Force outboard, 1995 -- how do I get more RPM's???

I had a fuel supply issue and carb issue lately. I replaced all fuel lines and removed the three carbs and cleaned them. Everything sounds great and runs great but I can only get to 4,000 rpms, which is not enough to plane out. Before I had any issues when the boat ran perfect I would always get up to 5,000-5,500 at top end and run smooth. I have adjusted the double threaded link all the way out so when I have the throttle all the way down the slide on the sides of the carbs is fully down as well. It can't go any further so I think there must be another adjustment to be made. Possibly the screw on each carb which has a spring around it. I know these have to be perfectly adjusted to run smooth. Any suggestions on how to get more rpm's??

Thanks everyone, I really appreciate the help!

Do a compression test and then a spark test.
The screw with the spring has nothing to do with high speed.
It's a low speed air/ fuel mix screw.
That screw set at 1 and 1/8th turn out until the high speed problem has been fixed then adjust.
You change props? Big load on the boat?
http://youtu.be/tDoR64jP5l8 Try this link. for a linc and sinc of your carbs and linkage.

Thanks for the advice. I had a compression test done not too long ago and it was great. I just changed the spark plugs but perhaps the cables went bad although they look to be in good shape. How would you suggest I do a Spark test? The prop is the same and there is not a load on boat. Everything is the same as it always has been.
So, perhaps you can walk me through how to do a spark test...
Thanks again.

Buy a spark tester at Auto Zone or any auto parts store.
Ground it on a good spot and install it on the plugs.

Compression was good a while ago ?--------How is the compression today ?---------Water pump been maintained ?