2009 Toyota Matrix Q&A

2009 Toyota Matrix Question: why does car ideal rough when foot on brake and car in gear

it doesn't do it all the time, it has only done it maybe 5 or 6 times -
Answer 1
Is the A/C on or off when it feels rough? Or does it make any difference? -
Comment 1
Yes the a/c was on -
Comment 2
when it's not on does it feel smoother? Maybe mount(s) are weak. -