[Vwdiesel] Power down Pyro up

[Don Kesler]

On the last 2 trips out in my boat, my cruise speed has decreased from
3200 rpm to 2600 rpm because the has been lost and the pyro stays hot. I
have had to back off the throttle because the pyro goes up. I don't know
what the limit is but I backed off to keep it under 1050 degrees. Before
I got 3800 rpm full throttle, now I can only get 3200 rpm.
I thought when you have a loss of fuel delivery, The power would
decrease but the pyro would also decrease. I checked one spot in the
exhaust (that was restricted with exhaust crud) and it was clear. Down
in the outdrive is the other point that might be restricted. The
outdrive normally is OK for a 5.7 gas engine. Mine is a 2.8 liter Isuzu
turbodiesel with 10 pounds boost
The water temperature is normal.
I have not checked the advance, but I have no reason to believe it has
changed.
Any clews as to what might be wrong?
Don