71 baja with a 1776 and a weber 44 IDF, took it for a 4 hour road trip today, 2 hours there killed about 2 hours with friends and family and 2 hours back. Cruising speed averaged around 65-70 getting there, coming back speed was 70 to 78, 4 miles from my home exit the motor started loosing power and made some popping sounds, top speed was 50mph all of a sudden. I pulled off the freeway and stopped motor sounded normal and had no hesitation revving it up, I returned to the freeway and was crusing at 70 again.
Any Ideas on this issue?

 

What your describing sounds like a backfire. Did it feel like it was running out of gas then make a noise like a gas shot? Backfires are caused by timing issues.