Hey Scotty! I have a 2007 pontiac g5 GT with 140 000km on it and once every 3 or 4 times when I start my car my RPM jumps and at the time time there is a rattling noise (like marbles spinning in a can) thats lasts from 1-3 seconds from the engine. Any thoughts on what it could be?

bad news knowing those. Internal engine wear normally. But make a video of it, post it here, and i can listen