Even more reason for not letting them export their oil

It's literally American money as you said. Instead of giving them full toll exemption, we should choke the Iraqi government off, who is not very that friendly towards Iran anyway, and force them to either get their shit together or face consequences like the rest of the Arab countries near the Persian Gulf.
As I said, we are too kind with Iraq, who killed over 300K Iranians during the Iraq-Iran under Saddam. They do not deserve this kind treatment and historically, they have been known to be betrayers to Imam Ali, Imam Hassan and Imam Hussein.