My engine has a strange characteristic. It's a 2.4 V6, FWD with multitronic auto. For almost the entire rev range, it's every bit as smooth as you'd expect it to, but at 1800rpm, there's a noticeable tremor. As soon as the rev counter goes past 1800, it smooths out again. I don't think it's gearbox related, because if I rev it to 1800rpm in neutral, it still does it. I've no idea what is causing it, and nor has my local dealer or indie (I asked both). One of them said it might be the dual mass flywheel, and the other said it didn't have one! After reading some threads on here, I was wondering whether fitting one of these might help. Ideas, anyone?