Hello,
My 300e ('89, 130,000 miles) runs fine when the engine is cool during cool weather but during warm weather when I come to a stop after running continuously on the highway the engine will miss on several or all cylinders at idle but not die. Usually this will stop after I drive moderately around town but it still happens occasionally on a hot day when I'm in town. I have also seen this happen after being parked at an idle for about 20 minutes with the ac on and the problem got progressively worse until the engine almost died.
I have replaced the fuel filter, fuel pump (one of two), fuel injectors, spark plugs and wires, distributor cap and rotor within the last six months so I assume these aren't part of the problem. I have a new coil on the way but somehow doubt that that's going to help much.
My mechanic thinks it's the oxygen sensor (hasn't tested it but says he can) and has suggested I first try a bottle of fuel additive in a tank of gas to see if that helps. I did just have the valve stem oil seals replaced because the plugs were fouling in 3 or 4 months. Could the O2 sensor have been affected in the same way as the spark plugs and be causing this problem?
Many thanks,
Mike