Semi-bluffing in multi-way pots

[lgkeeper]

I've run into this a few times lately and haven't really handled it well. Any help is appreciated.

I'll give a hypothetical, but the general question is, in position, do you find it +EV to semi-bluff in multi-way pots?

For example, 180 runner, 150 left (still early), hero has avg chip stack, blinds at 50/100 and hero has 3000

4 players limp to you OTB and you call wihh 89[img]/images/graemlins/diamond.gif[/img]
SB completes, BB checks and flop is
7[img]/images/graemlins/diamond.gif[/img]8[img]/images/graemlins/spade.gif[/img]J[img]/images/graemlins/diamond.gif[/img]

So you have middle pair, and a flush draw (with a gut straight flush draw).

SB bets 150 into a 600 pot and gets 3 callers to you.

It's early, but you have a biggy...what do you do?