WWoooo Hoooo. Pressure is back where it should be. Temp is good, like it was. Life is good for now. lol. After a few Heinekens, I will post what was the problem. (with pics) BTW a $10 item. What an ordeal, but I have a boat again.

I offer this so NO ONE has to go through this BS. I been using "T" clamps for years. IT is a better clamp then the standard or even HD hose clamps. SO I screwed up in reverse. I do check the tightness of the clamps regularly, but I forgot about the rubber hoses having a "memory". See old hose with the typical clamp markings. After some time the hose actually retain it's compressed state. No biggie, you tighten the clamps and off you go.
Unless your clamp is tight already, as mine was at the impeller housing, BUT While it was tight and could not really be tighter, the hose actually retained a smaller diameter so while the clamp was tight the hose did not "compress" any further. See Pic "A" there is no more tightening possible on the clamp. It's fully "closed". Pic "B" shows more room or space to have compression. Both are about 1 1/2 " to 1 3/4" in the picture. (for typ Heavy wall tubing) Clamp "A" , I could not compress anymore, it reached it's limit. So while I thought the clamp was tight, the actual seal was apparently not tight enough. It was sucking in air at higher RPM's. Once I replaced it with a "smaller" clamp, due to the hose with age is actually smaller OD. The problem was solved and all is good. Smile at my mishap, but remember it.
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Good to know and thanks for posting. I always try and twist a hose after tightening to make sure but don't know if that would have helped.

Fantastic!! Glad it was simple.

I'm glad you found your issue!!

lol.. Right... 6+ Mo. of headaches.

Sorry to grab out this old story!! But it was very intersting for me,as i have same probs at moment!
I do some work at engine,600sci,in winter like headers away and so.
Now add an Sportmaster lower to the XR Upper and lost waterpressure.it will not go over 20Psi.Last year was allways over 30 with DWP Lower.
Like you, i have checked all stuff like waterpump,fuelcooler and so on.
Test the Pressuresender smartcraft today with air and my system shows the pressure i give to sender.So this work good and real loose pressure.
I have an T part in the line to waterpump for flush the engine.Will check tomorrow all clamps there as i nevver belive that a small leak there can make so much trouble with pressure.
will see!!
I will not belive that a Sportmaster with LWP will bring down Waterpressure.Normally pressure go up with this or not?
Thanks for your search story!
Michael