Have gapped the plugs and checked for evidence of oil in the cylinder.

Plugs for absolute certain. Probably also motor mounts.

You changed plugs 57,000 miles ago? You, my friend, almost certainly need new plugs.

How frequently is oil changed? Synthetic or conventional? Check filter and drained oil for metal particles. Might be worth dropping the pan and checking for any sludge.

And motor and transmission mounts are probably shot. Can you have someone shift the car between D and R while depressing the brake and accelerator pedals as you observe the engine bay?

Anonymous wrote:

Anonymous wrote:You have a miss and need a tune up.

Tune up was done at 100k. You think I have a bad plug? If so, wouldn't it rattle at P/N as well?

Engine's not under load in P/N

Anonymous wrote:You have a miss and need a tune up.

Tune up was done at 100k. You think I have a bad plug? If so, wouldn't it rattle at P/N as well?

You have a miss and need a tune up.

I just wanted to add one more detail - I don't just hear the sound (like loose heat shield), car actually rattles. I can feel it via brake pedal.

2009 honda accord, 4 cyl, 157000 miles. Car slightly rattles/vibrates at stop lights (gear in D) - just enough to annoy me. Worse with AC on but no rattle when P or N. What would be your guess? I am thinking engine mount may be bad but what other possible reasons??