[ddrstel]

There are a lot of scary turn cards that will kill your action and shut down anyone willing to get it in with you... get as much money in on this flop as you can.

Lots of limpers could mean two pair or a pair and a gutshot type holdings.
Raise to 5 and pray for a reraise. Re-evaluate the turn based on action. If no one calls your flop raise, then there was no money to be made on this hand anyway.