[shark6]

You flopped a great draw, open-ended straight plus backdoor flush.

I would check call the flop. By betting, your allowing the PFR to potenitally raise and knock out the MP2 by making him call 2 cold. I know MP2 is loose and may call anyway.

But, with a flop check/call, you can trap MP2 with a check raise on the big streets, plus you get more money out of the PFR when you raise on the turn.