Cause & effect.
If you manage to stop the steering wheel rattling, it may not necessarily have addressed the root of the problem.
How does the engine sound when idling at 900rpm. Is it a bit lumpy, rocking a bit on the mountings, etc. Poor idling can be down to a myriad of things: fuelling, induction air leaks, ignition, etc.
when was it last serviced…plugs, filters, etc?
