engine mounts

Hi. How do you know 100% that the engine mounts need replacment. The engine has a rough idle in drive and when I stop at lights. RPM is good, just changed the air filter and cleaned MAF sensor ( I thought it would be this ) but the problem is still there. I'm trying to figure out how to check if the mounts are bad. Thanks.

Take a look at the roll restrictors under the car. You can usually just look at them and see if the rubber within the mount is intact.