You should exploit the fact that CO 3 bet so his range is never a 4 here. When you call pre there is a slight chance you have 4's but mostly your range with exception to the A misses that board.
Therefore two conclusions can be reached:
1) He is never on a 4 here. His range is capped to Ax type hands by the river.
2) You almost never have a 5, and rarely have a 4 here, the CO knows this
Based on that action, and the fact that he almost never has a full house here you can jam here for max value. He cannot fold as you have too many weaker Ax hands that can open from MP yet call a 3bet.