420 SEL idle misfire

[bighillman]

I have a 1988 420 and it's got a misfire at idle only. It had a fuel leak at the fuel distributor and I replaced that and thought it might cure the miss too. I've adjusted the plate and it made the car faster, but the miss won't go away. The misfire is coming from the front and back cylinders on the drivers side of the engine and is more pronounced when it's at a stop with the transmission in drive. The spark plugs out of the misfiring cylinders are fuel fouled and I couldn't find a vacuum leak. Under throttle, you would never know the condition even existed because this car will haul the mail, but at idle, it's annoying.
History on the car. . . It's a friend of mine's. 140,000 miles. In the last 12 months. . . Had timing chain guides work done on it and camshafts replaced, it ran good for a while, then developed this goofy miss and they're tired of dealing with whoever worked on it before me. They had me put plugs, wires, a cap, and a rotor on it and it changed nothing.

[sammydose]

I have the same car, and have been through some of the same problems. Since my car has about 120,000 miles, I needed to address several problems in the fuel system, and also had to replace many of the bits of rubber on the front suspension, and the mother of my radiator. I do not want to look at total spending, but I have a great car like new and not much more to be done for another 100,000 miles.