I just bought my car a little over three weeks ago and ever since i bought it i've noticed a strange rattling coming from the tranny since about 500 miles. Sometimes when engaging first from a stop i get a rattling noise, sounds like something may be loose. The noise also happens sometimes when downshifting into second or first. The other thing that i seem to have a problem with is a rough idle. It doesn't do it all the time, just some of the time. I've never noticed it while in denver, but up here at 10,000ft elev it seems to do it often. The car currently has a little over 1500 miles.

 

my car is a 6mt btw