When i put it in reverse it makes a loud clunk

Hi Ali,

This sounds like one or more of your motor/powerplant mounts is broken. Here is an easy test:

Have someone sit in the driver's sear with engine running and trans. in Park.
You stand in front with the hood open. Have them shift from Park to Reverse, and then Drive and back to Reverse and Park, taking time to stay in each gear and give some throttle while holding the brake pedal tight. This will rock or move the engine a certain amount as they shift through the gears and apply power lightly. It will move alot more violently with broken mounts.

If you have a clunking noise on Reverse shifts, you should be able reproduce this with the hood up and pinpoint the noise and/or sight the faulty motor mount with a friend's help. Good luck, I hope this puts you on the right track to fixing this annoying noise.

Sincerely, Tater Todd

I understand this is a 5 year old post, but this solution may help others in the future. To address the vibration problem at a light (in D with brakes applied) I would like to suggest that your timing belt may have skipped a tooth at some point. I just discovered this when changing out a failed Left camshaft oil seal on my 01 Outback 2.5. Once I got the timing belt cover off, I aligned the crankshaft marks and the right side was dead on, but the left side was one tooth off. I changed out all the seals, and replaced the timing belt, aligned the camshafts up with the crankshaft properly and the idle has smoothed out completely.