I pulled off the inline solenoid and line and replaced it with the new solid fuel line. This time it continued to run well above 45-50mph.
I cannot explain why this test failed previously unless there was some debris in the main shut off valve.
Yes, I have replaced the bowl screen, checked and rechecked it. Have many in stock.
Regardless, I am calling this fixed! I will definitely add that stand up filter.
Thanks for all the input!!