when downshifting there is a rattling noise from motor like something is loose on 2002 Toyota MR2 Spyder

What could cause this noise. It also has started backfiring.

Asked by for the 2002 Toyota MR2 Spyder
do you still own your MR2? if so are you still happy with it? I'm considering one now, haven't been inside one yet but wondering how comfortable the seats are so someone not very small or thin?