UTG 42/3/36. No concept of position. Previous hand he had limps UTG+1 w/ QTo, called a raise, and called a flop bet with overcards, no draw.

1/2 Limit - Full Tilt
UTG limps, I raise [Js] UTG+2, folded to UTG who calls.
[Jd][Qs] Pot 5.5 SB
UTG checks, I bet, UTG calls
Pot 3.75 BB
UTG checks, I bet, UTG raises, I 3-bet, UTG caps, I call.

Anybody have any ideas what to put him on? Anybody worried?

Pot 11.75 BB
UTG bets, I raise, UTG 3-bets......????

I don't play much limit anymore, but I have seen everything in my day. I once got 15 bet on the 2/4 cryptos were a guy had top set versus my nut straight.

Here though, against most players I just call the 3-bet on the river most times here but play all other streets as you did.

Easy cap in my opinion here. Hands that play out like this will typically end up with you crushing the lower set. While the turn is a little baffling, I think more times than not you will see a 66/44 type hand.