I would be comfortable with a consistent 20psi. I know volume it more important than pressure. I am guessing that is why when my oil was "dropping" to 0 but I was not getting any oil starvation sounds.

The motor is in a rock crawler, not a mud bogger, so it sees a bunch of off idle beating/full-throttle hits. That is why I am concerned about low idle pressure, but with 20w-50 I am seeing better pressure once it gets hot.

I think your original idea of it being from getting too hot is right on the money. I am going to go ahead a swap pumps out though since after doing a ton of reading it seems that the m-77hv is not what it used to be with powdered metal gears and horrible factory tolerances.

Clay