My 89 civic dx hatchback has an odd rattling noise. When at low rpms with the engine being gassed. *I can be in 3rd or 4th with low rpms and not giving much if any gas and it doesnt happen.* It starts to rattle. As soon as it hits a higher rpm it stops, or as soon as I let off the gas it stops. At first I thought it was the exhaust but I doubt it would only rattle when accelerating. Any thoughts?

 

Really tinny, metallic rattling from under the center of the car is usually a heat shield. Put the car up on ramps, crawl underneath and shake the exhaust parts around.