Boltneck, the way you had him figured is almost a classic WA or WB. I'm not sure what the best way is to handle that in fixed limit. You chose the safe way. The fact he check/raised the turn rather than the flop doesn't really give you any certainty about the strength of his hand. He might make such a move with AJ because he figures he's now crushing any stronger or weaker A, which ultimately is the reason he did it and you knew there was a decent chance of that.
As far as losing value, that's just a maybe, because pot was 3-way. On the turn you flat called the check/raise and that kept 3rd villain in the hand. If you raise again he might fold, which is not a bad thing because keeping him in gives him a chance to outdraw you. But I'm just trying to say that if you raise and 3rd villain folds, on the river pot could be same amount, and at that point, after your turn 4bet raise, the remaining villain could just go in check/call mode. Sorry I know all that is a bit confusing but I'm just trying to show you that even if you raise the turn you might end up with a pot that has the same size of the one you took down, although in this scenario it's only 2 seeing the river so less chances of getting outdrawn.
I don't think you played this bad, because your hand, even if very strong, didn't improve and you were squeezed in the middle of both players. The turn didn't complete any straights but that doesn't necessarily mean you were ahead. You got check/raised with a player left to act. I'm not saying you have to be worried that 3rd villain is going to raise again because he didn't the first time, but you start to wonder if you're ahead or behind. I think I play it the same way you did on the turn, and after that 8 showed up on the river again I think I'd just call because QT is certainly in 3rd villain's range. Given how passively he played this he does look like he's on some kind of draw. Maybe a limit expert would play this differently, but to me your line looks fine.
I think the better question is this. If the pot were HU rather than being 3-way, what would you do? Would you raise at some point, on the turn or river? Or play it the same way you did? Because if pot were HU then value comes into play even more than it does now.