mudcakez

Hey guys, just a few questions. My RX has a bit of trouble cold starting as shown in the video; it can take up to 1.5x longer and sometimes it will start to kick over but struggle for half a sec before the revs go up. Seems to happen regardless of outside temp and severity is irregular. At around 0:32 I start it again after being warmed for 5 minutes and it's completely fine.
 
Another problem shown in the video is this rattling sound that I think is coming from the mid to rear of the car. Happens on cold starts, when I try to take off in 1st or reverse without giving it enough throttle (0:43 in vid), going over humps and sometimes when I turn the engine off. Hoping it's just exhaust rattle, haven't had a chance to check it out yet but doesn't sound the same as other exhaust rattles I've heard in vids.
 
Any ideas? Cheers everyone