Well update everyone I found a big problem today, after doing some vacuum system troubleshooting I found there is no vacuum going to either the VCV or the modulator on the transmission. So there is a gross vacuum leak I need to find and fix and then go after the shifting problem again. Knowing this I now know that the transmission actually only had first and second gear and would not shift into third or fourth because there was no vacuum. Also just finished running fresh atf through the transmission after letting the contaminated fluid drain all night, so the fluid on the dipstick should be bright red soon after I test drive it again once this vacuum leak is fixed. I'm used to the 722.1 transmission where it starts out in 2nd gear unless there is a load behind it. So that makes sense that the internal governor in the transmission was manually upshifting the car to 2nd gear during the test drive. (Note the governor will only upshift from first to second and vice versa, it will not upshift to third or fourth.)