Iran's a natural flashpoint. Under what circumstances do you think China would stand with Iran against the US? I agree about Iraq - they want it settled, we want it settled.
I take it you mean a military stand whereby China commits military force to defend Iran against the US.
Only under one set of circumstances can I imagine China committing troops. It would be part of a prior decision by China to go to war over Taiwan.
But, I don't think China needs to commit troops to make a stand with Iran. What I think they're doing is providing technology and weapons and providing strategic and tactical planning assistance. You can bet they've made a close study of Gulf War I, Yugoslavia, Afghanistan, and Gulf War II. They've probably got a lot of (theoretical) knowledge to sell the Iranians.
The Chinese military doesn't exactly have a glorious military record, anyway. They're still flushing crimson at the humiliation handed them by the Vietnamese. And, their general officers have acknowledged at various times, recently, that they cannot win a conventional war with the US. So, that brings us back to Taiwan, I think, and the prospect of nuclear war.
Now, should Russia and China accept Iran's request to join the Shanghai Cooperation Organization, that might signal something as dangerous as Taiwan.
But does China have the internal security and the nationalist fervor to face the consequences of a real war? I tend to think they do not.