I just installed new spark plugs, ignition cables and distributor cap in my brother in law's 1991 MB 300CE. It runs much more smoothly now, has stopped mis-firing and has power when you press down the accelerator, but now it vibrates and shakes when idling...not always but often enough to be perplexing. Could this be a bad motor mount? It has 89K miles on it.
Thanks in advance for your thoughts on this.