Possibly an Iran that tries to form the Shiite Crescent by force and succeeds, and gets nukes in the process. Sort of ASB, however, as the Russians would pinch them from the North mercilessly if they tried that.
Iran avoids islamic revolution - however, islamic revolution happens in some other coutries.
War on terror starts a bit earlier as OTL.
Westernized Iran (American ally, dictatorship of the emperor) starts to invade neighbouring countries on the pretext of fighting islamic terrorism and bringing western values to these countries.
When Iran invades the Arabian Peninsula, everybody realizes that this country has grown to big and is going to control the major part of the earth's oil.
Iran is stopped by an international coalition.