Well according to Geo. Murphy the last sensor on the head is the one you want, and the wire color is green w/ red tracer also I would stick w/ the 470 resistor as this is what is suggested.
I have not done this "upgrade" so your on your own.
BTW I also understand there has been an upgrade with the fuel pump relay giving a little richer idle, at warmer temps?
My 86' 300E had same type of problems, a new O2 sensor really straightened things out.
The clunk, maybe the bad mounts?