that ctd is weird. we haven't had any of those in ages. you don't happen to have a save?
as the Anitogonids I had success this way:
put tech to zero at first and hire all the Greek heavy spearmen who appear.
don't rush anyone, wait for them to expose their armies by coming at you. don't try to kill the Seleucids, just kill their starting stack and take a couple of cities, including Babylon. then declare war on them again when Parthia spawns.
give stuff to the Romans, gold and techs. declare war on carthage if they do. if they get conquerors abandon their target city and counterattack with 1 or 2 catapults + peltasts.
you will share a war with the Parthians (vs Seleucids) so they should be friendly
for stability, Greece is in your core so you need to control it and grow its population. use GP for golden ages .
edit: when you played Armenia, how early were the Romans in Syria? I'm surprised you got anarchy then since you must have been only controlling your core.
to be clear about stability, I'm not trying to make a punishing system. its still being adjusted. it should be easy to stay stable as a small civ in your core, more or less automatic. it should be possible to build a large empire and stay stable as well, provided you have the appropriate buildings and civics, a high core population and a reasonable economy.
edit 2:
changed the Colossus effect from global to local, like the other pre-placed wonders
finally got Multan and Lahore in the right places on the Indian civs settler map