rattling sound

[MainTriscuit]

I have been noticing lately that after I start my car and leave it run for a few minutes, I put it in reverse and back up and there is a rattling sound coming from the engine somewhere, it sounds like metal on metal and when I cut the wheel it gets louder. I have injen cai and I checked to see if that was rubbing anything and I didnt notice anything. I had my friend start the car while I was outside of it while the hood was up. I told him to almost stall it while the e-brake was on and I noticed that the engine shakes like crazy. Would a motor mount fix this problem or is it more serious? Any help would be great, thanks

Matt