[SnipesXxX]

I have a 2000 Grand Am SE that has over 130,000 miles on it. It's been a good car and is drove almost daily. For a year or so I've noticed once the car warms up and is at a idle I notice a pecking or light knocking sound. It gets louder with the AC/Heat on. I haven't really looked into the problem though. I took it to have brakes done on it and figured I would mention it to the mechanic and he said it was normal for those engines(4 cylinder) and sounded good compared to some that came in there. The noise goes away if you barely give it any gas at all and sounds fine.

Curious what would cause this? I am guessing it has alot to do with the engine having alot of miles on it. Is it something I should look into fixing?

One last thing how often should one change spark plugs on these cars? I know they haven't been changed since I got it a few years ago and it had over 80,000 on it then.