Typically play 2/5 but decided to take a shot at 5/10NL.
I don't recognize any of the players

MP raises to $40.
I call with KJ in the cutoff. The button and small blind both call.

Flop ($170) A94

Checks around

Turn ($170) Q

Small blind bets $85, MP calls, I call, button folds.

River ($425) A

SB checks, MP checks, Hero ?

Small blind looks like a young Internet kid. MP is middle aged.
MP has $400 behind, I have $1K, SB has me covered.

Is this a good spot to bluff? If so, what sized bet?

If I bet small, I could get called by a Q.

If I bet big, it looks a lot like a bluff. Both flushes missed, the straight missed.

Would I play an ace this way? If I had A9,AT,AJ,AQ I would probably have bet the flop and if I had a weak ace I probably would have folded preflop but they don't know that. I guess I could have a suited wheel ace sometimes: A2s,A3s,A5s (not A4s because I would have bet the flop).

Would I play a set this way? If I had 99 or 44 and decided to check back the flop, I almost certainly would have raised the turn.

So in conclusion, I don't have a lot of value hands here. But who knows if my opponents realize that.

Even though I can't really represent a hand, a bluff could still work if both villains have weak hands themselves. If they were straightforward players then I would assume that they would bet an ace on the river.
What are the chances that one of them has a strong hand (ace or better) and is checking at the end to try to induce a bet?

I will post the results tomorrow.

Your best bluffs are probably JTcc and JThh and your value bets are gonna be Ax that checked back flop and maybe KQ so I guess it depends how often you xb an ace otf. I'd check this back especially cause we have zero full houses and sb can still have some. Also our check back has > 0 EV cause we beat the other flush draws. If you feel you need to find more bluffs than 2 JT I'd pick some lower diamonds or spades that checked back the flop (although I guess we don't have too many of those hands either)

Thanks Jarretman, I like the way that you think.
Then we should bet 1/2 pot with our JTs bluffs or a bigger size to try and get QT/QJ to fold?

This river is tricky because of how capped we are vs SB. SB can still have AQ/A4s/A9s/44/99 that decided to not 3bet pre and x/r river; we have close to none of these hands (I guess we can have some AQ that didn't raise turn?). MP is kinda capped as well so bottom line is SB should be x/r jamming this river pretty aggressively vs a CO bet, when he does check the river, and it's not like it's hard for him to find bluffs.

I'd probably bet $200 given that MP has $400.

I guess bettin 400 is gonna be higher ev than checking here he’ll have fold quite often here

I'd take my minimal showdown value here. I think the whatever percent of the time we win the pot is going to be worth more than a bluff here (mostly don't expect sb to fold many value hands he bet the turn with).

I check river.

I strongly consider betting flop with backdoor nfd and backdoor straight draws and very good equity against anything that is not an ace.

that flop is dis connected enough that we need to be creative to find bluffs..