Sure they do. Under the Shah they sent tons of troops into Oman and after 1979
Wrong - there was no Iranian invasion of Oman or even war between Iran and Oman
they actually did try to conquer Iraq during the Iran-Iraq War. They moved Saddam's troops of their territory really quickly and then spent the rest of it trying to take the whole country (Saddam sued for peace several times and was rejected).
Wrong and wrong. It took the Iranians over 18 months to remove the majority of the Iraqi forces from Iranian soil. After some debate within the Iranian administration it was decided to continue the hostilities into Iraqi territory with the intention of triggering regime change (somewhat similar to the US in 1991).
They also sent Quds force all over the Middle East. It would be completely in character for them to do that if they thought they could get away with it.
Huh? In what way is sending military resources to established allies a conventional war of choice?
It is true that there were people in the Bush administration that were looking to invade Iran. It is not true, especially in this TL which implies that there is a more rational U.S. leadership, that this was ever going to happen.
Wrong. The US (and its Sunni client states) intervened in 1982 with finance, weaponry and intelligence when it appeared Iraq might fall to a potentially hostile Shite Iran. Again the US (and Sunni client states) intervened in 1991 against Iraq when it appeared Saddam might control too much strategic oil reserves. The Bush administration initiated a war of choice in 2003 against Iraq, but in the case of overt Iranian hostility, it would be a war to maintain the status quo - a defensive war that everyone can support.
The reason Saddam got knocked off was because he relied on genocide to keep himself in power, invaded all of his neighbors including several crucial U.S. allies, and forced the U.S. to take tons of military actions against him. He also just plain went out of his way to act out whenever he should have done otherwise by supporting the PLO in the Second Intifada, celebrating 9/11, and other stuff. That was why we went in.
Wrong. The first US intervention in 1982 (was to support Iraqi aggression) and prevent a regime sympathetic to Iran gaining power and control of strategic oil reserves. The second intervention against Iraq in 1991 was to protect US client states and safeguard oil reserves. The US third intervention in 2003 was an opportunist grab for resources arising from the aftermath of 9-11. According to General Wesley Clark, within weeks of 9-11 the US had a firm plan to take out seven regimes within five years including Iraq, Libya, Syria and Iran. The only thing that saved Iran was the occupation of Iraq went tits up.
Iran just never did anything like that; they were smarter, and it didn't hurt that they were a lot larger and more powerful. The most the U.S. would have ever considered doing is striking their nuclear program. Going to war with them because they invaded Saddam's Iraq would have been an automatic nonstarter.
Really? You are saying the US [high on victory disease soon after Afghanistan] would abandon its client states in the Gulf, allowing its longest and most formidable rival in the region [Iran] secure Iraqi oil without a fight.
Seriously, can you imagine making that argument to the American people? "Yeah, they invaded our worst enemy in the Middle East, who we have been fighting for decades, which is somehow bad, so we're should go to war with them." Any government that tried to make that argument would be lynched in the streets. We wouldn't have done anything.
From 1982 the US actively aided the Iraqi war effort against Iran, despite Iraq being the aggressor. Until the Iraqi invasion of Kuwait in late 1990, the US continued to treat Iraq as friendly. The 1991 gulf war [including build up] lasted a little over six months and active hostilities a little over six weeks. Conversely, the US has maintained hostile relations with Iran since 1979 and has client states (or visa-versa) like Israel and Saudi Arabia that are also hostile to Iran.
In any case, around year 2000 most American people would struggle to find either Iraq or Iran on a map or distinguish the difference.