Cooler plastic, and holding pressure should do the trick, but it has it's own issues.
As seems to be my wont, I shot myself in the foot again.
This time, I made a 6 individual cavity pop mold with a fat, long profile.
Because I wanted to keep denting to a minimum, I injected at 325.
Because I hold pressure on the injector for a five count before I move to the next cavity, I can only inject four cavities before the plastic cools too much.
I don't preheat my injector, which I'm sure would help.
The mold came out good, so I'll just do four cavities at a time, and be happy that it works.