should I raise this river bet?

[SenecaJim]

5-10 live

2 early limpers. I raise in MP2 with AKo. All fold but BB and limpers.

Flop comes A K 4 rainbow. Checked to me, I bet, BB folds, limpers call.

Turn is a blank. ( don't remember, but blank.) Both limpers check, I bet and am called.

The river is another 4. The first limper now donks into 2 of us. MP1 calls. I call or raise? No particular read on donker,loose preflop and usually calls down.