1. Enforce true and fair sharing of the oil revenue. Base it on the Alaska Permanent Fund model. Then the choice becomes get money or die in the continuing fighting: Most people would prefer the money.
2. Build up the Iraqi army to fight Al Quada, send them to Afghanistan. AQ is actually Iraq's enemy, the USA are the good guys in this fight but have been terribly managed. This would get a lot of fighters out of Iraq, pay them, align them with the USA against AQ.
Simplistic suggestions but why not?