I think raising pre is ok, his limp is usually a weak hand like a small pair or 2 gapper suited connector type bs. Unless he limps big overpairs and does things like this on the flop which wouldnt surprise me. 20-17 tho tells me he prob. Raises his premiums and open limps/flat calls ipwith s.c. And small pp type hands. I highly doubt he has 77-88 here, my assumption is a set, 2pr, or the nut str8. As played I fold to check raise as our overcards are never good in this spot. We have a naked flush where all our outs might not even be clean.