Here is the problem, low water pressure (14# @4000rpm) oil and water temp starts to go up . here is what I have checked:
Pulled lower unit inspect "o" ring--ok
Checked drive to gimble "o" ring-ok
Checked hose and 90deg fitting on gimble-ok
Installed new water pump
Checked power steering cooler-ok
my water pressure is installed in-line after the p/s cooler as shown. The motor is fresh water cooled even the exhaust and I am not loosing any anti-freez or getting water in the system. I installed a clear hose after the pump and it does not show any air when running. I would think the pressure would go up if it were blocked after the water pressure tap and a restriction would cause low pressure.

You said you checked the 90* fitting, but did you pull it off. I had a simliar issue last year. I ended up finding a clog behind part # 20 in the attached picture. I had to pull it apart to tell.

http://www.mercruiserparts.com/Show_...Gimbal+Housing

Yes I looked at it very close at that.

ttt

Often the gimbal housing corrodes (#15 &#16) causing a restriction. If you remove #20 as pictured with Vinny's attachment inspect this very closely.

I am at a total loss I swaped the hose from the 90* fitting form port to starbord and tested. problem followed so it has to be the hose in the transom assy. right. changed it out found nothing. put it back together same thing. WTF.
all the orings are new. yesterday I pulled every hose off the cooling system, stuck a wire through every hole and found nothing.

One of the hoses before the sea pump is most likely collapsing under suction.

I change the one in the transom and when i swaped the port to starbord and starbord to port I used 2 new hoses.

what motors are you running? I had problems with my 600 efi and I am not the only one. I finally figured out the fix. Do you have a external bottom pickup?

502 EFI with xr sportmaster lowers, it does the same thing with the standard bravo lowers.
Does everyone agree that a high pressure would be a block after the w/p guage. a block before the w/p guage would cause low water pressure.