On the “evil” done by Ahab, see especially 1 Kings 16:30-34. Jehoram, warned by the fate of his brother (2 Kings 1:4 note), began his reign by a formal abolition of the Phoenician state religion introduced by Ahab - even if he connived at its continuance among the people 2 Kings 10:26-27; and by a re-establishment of the old worship of the kingdom as arranged by Jeroboam.
Related Commentaries of 2 Kings 3:2
2 Kings 3:2
2 And he wrought evil in the sight of the LORD; but not like his father, and like his mother: for he put away the imagea of Baal that his father had made.