Sludge won't hurt anything as long as it stays in place and isn't loosened up. Have the intake manifold replaced and don't try to remove the sludge and it will be all right. I would have the oil changed, but wouldn't run a flush through the engine, 'cause it will loosen all the sludge and start clogging the oil filter and possibly the oil pump inlet screen.
There are 2 opinions about sludge build up. 1 is to disturb it as little as possible and 2 is to completely clean it out. I go along with leaving it alone.