I need some RB/TE help?

I need help fine-tuning two of my positions on my fantasy team. I currently have Willie Parker, Matt Forte, and Michael Pittman at RB. I'm considering dropping one of them to pick up Chris Perry, who I had earlier, but dropped due to poor performance--now, of course, he has started playing well. Should I drop one of my current RBs for Perry? If so, who? Also, I have Dallas Clark and Robert Royal at TE. I had Anthony Fasano, but due to a bye week, dropped him to pick up Royal. However, my main concern is with Clark. He has been performing poorly and is wasting space on my bench. Should I drop him?