If you typically get 3 callers with this open UTG either open bigger or just fold. I hate playing AJo from EP in multi-way pots.
As played, are there any strong Aces in his BB flat range? (AQ, AJ?).
Vs. the range you provided you have roughly 40%
www.pokerstrategy.com
Board: AdKh9h
Equity Win Tie
UTG 38.97% 36.36% 2.61% { AJo }
BB 61.03% 58.42% 2.61% { 99, A9s, K9s, KhQh, AhJh, KhJh, QhJh, AhTh, KhTh, QhTh, JhTh, Qh9h, Jh9h, Th9h, Ah8h, Th8h, 9h8h, Ah7h, 8h7h, Ah6h, 7h6h, Ah5h, 6h5h, Ah4h, Ah3h, Ah2h, A9o }
Not the best of situations to get your money in. Even if you call and a blank comes on the turn your equity doesn't improve much. You have to give him a LOT more flush draws in his range to get yourself in a position where you are a 55-45 favorite on the flop. You say he's decent so that's unlikely. I would fold and find a better spot.