help me know if I should have folded suspecting the Villian had suited conncetors

First of all, raise this pre!

As played, bet flop yourself for value. Turn I just fold facing a bet and raise in front. It's a limped pot so they can easily have all two pairs and straights.

You should definitely raise this pre and start betting yourself OTF.
As a general rule I would say that never go broke in a limped pot without the nuts. Both villains can have anything, so your call OTT with a weaker hand than TPTK was bad.

Is it always a good idea to raise pre-flop when you have a playable hand, about 3 or 4 BB?

No it isn't always so. Some hands thrive in cheap multiway pots, others don't. This one can be played either way. Most, including me, would raise.

But the question of the thread is "should you have known what they had"? No, you don't need to figure out what they hold exactly. Just figure out that their actions tell you are beaten big time almost every time.

The best part about raising pre with a playable hand, in stead of calling, is that you can represent more hands on the flop that wouldnt be in your range otherwise.
For instance, bc you call, you basically delete tophands (JJ+, AK) out of your range or are at least "less likely".
If you raise, your continued aggresson OTF is more likely to get folds from better hands in case you don't hit, and you get a bigger pot if you do hit.

Always be cautious with toppair, especially if you dont have topkicker. In multiway pots with lots of action, TPTK is almost never enough. Toppair with a good kicker is certainly never enough. This should have been a super easy fold OTT.

I can't see any explainable reason to call ott, the turn card sucks!