I have an 1988 300e that has a rough idle at initil cold startup that lasts for about 3 seconds and then it is fine. I have replaced wires, cap, rotor, plugs and it is still there. The car uses no oil or antifreeze as that was my first thought that might be causing an idling problem (fluid in one cylinder). Also, occasionally I will feel a very slight miss at idle. Car runs and drives perfect except for at idle. Any ideas?