Is it permissible to consult an imam who practices divination regarding marriage, knowing that I have already prayed Istikhara?

One must avoid this man who writes things and reads them, then issues instructions to advance or retreat. One should also avoid believing him and instead suffice with the legitimate Istikhara (guidance prayer) and asking Allah Almighty to facilitate what is good for you. Especially since scholars have favored prohibiting taking omens from the Qur'an, it is even more appropriate to prohibit taking them from things that have no basis in Islamic law.