Hi folks!
I have an '87 300e with a 103 engine. The engine surges when idling. It doesn't seem like it's miss-firing, it idles smoothly and every second or so it increases in speed by a hundred or two hundred rpm. In addition, my plugs have a lot of deposits on them. The deposits are black, fuzzy and very thick (like a very rich mixture). The surging continued with new plugs. Oil usage is about 1qt per 1000miles (I use Mobil 1 oil). Compressions run about 145 psi. I recently purchased the car with true mileage unknown.

It has been suggested that the injectors need replacing, I'm wondering if this could be a timing issue, fuel pressure issue, or an oxygen sensor issue. I'd feel better about replacing the O2 sensor if the light was on, but I'll replace it if the forum feels it would be wise.

Thanks in advance all!

Bob