I have recently came upon the topic of sortition and it seemed interesting to me as a way to "fix" democracy. When talking with a friend about it he mentioned that it was used in ancient greek polises and it very often plunged the polis into chaos and even war between factions. After some searching I couldn't find something to back up his claims. Upon reading the Wikipedia page for sortition I see only Athens listed as a greek polis using the sortition method around 6th century BCE.
Did ancient Athens experience a greater deal of political instability related to other polises which used the more known method of elections?
Sortition was considered the democratic way to select political officers, thus it was used by all democratic Greek cities, not just Athens. Elections were used in oligarchical cities, such as Sparta.
As for instability - the Athenian system was in fact quite stable. This system reached maturity in the 4th century BC and experienced no serious upheavals for decades until it was defeated by the Macedonians in 338 BC.