Heatshields are best thought of as alarm bells. If they are loose, then (IMHO) the car sounds like it needs maintenance. Repair the heatsheilds by re-welding the join (its a small weld that you could probably do with liquid weld that is sold over the counter). But look over the suspension, the shocks, the steering feel, and even things like the balance on the tires (an easy check and fix)