180 players, we are at level 4 of the tournament, blinds 150/300/25, I have 14k chips.

An older gentleman with a stack of 28k raise UTG+1 to 900.
So far from early position I've seen him open limp AJ, A9s, KQo and raise AA and QQ.
I also noticed that he was trickier and more skilled after the flop. than I would have guessed.

I call in UTG+3. HJ calls and BB calls (both have around 10-12k)

flop comes A96 all spades and first raiser bets 4000

I have AJ with the jack of spades.

What should I do ?