sl 600 rough idle

[supermike]

hello to all,
i am new to this website and found it very informative. i just got a 1995 slo 600 with 62 k miles. my problem is the idle is rough during in neutral and less so in other gears. the tachometer swing aroung 700-800 and i can feel the car shake. the engine mount was just change when i bought it. i did some research on this forum and put techron additives in without much help(although i noticed the acceleration was slightly smoother) i have read about vacuum leak. my question is could this be due to vacuum leak? i noticed that the vacuum pump is working off and on every 10 minutes while i drive. i also noticed that when i unlock the car with the remote and heard a sound of air leaking near the passenger side area follow by the operation of the vacuum pump. any advice are graciously welcome.
thanks
mike