Thanks for all who tried to help , But as is posted this is one of the quirks of the jet drive

The rake is a good idea , I have already bent a copper pipe and installed a small rake head on it so I can clean the drive grate from the boat. I did get a hold of someone in NY who tried screens and when he put small enough screen on the boat would just cavitate above 1/2 throttle .
I have found the best way to "clean" the grate is to get the boat to about 15-20 mph (at no more than 1/2 throttle) and kill the engine letting the wake catch the rear of the boat, This kind of back flushes the jet drive and actually helps quite a bit but after that I still use the rake .
Thanks again for everyone's help ...