After the 4 month long rebuild, I was pretty tired of looking at an m117 engine, so I decided to send the car out to have the rough running sorted.
I had pretty must lost faith in most garages, but I thought I'd give Young Street Garage a try since I've used them many years ago with the 190E and was very satisfied with the work.
And by luck or by fluke, they found that the driver's side cam was off by 1 tooth. I was pretty impressed that they actually took off the valve-covers. In any case, they re-timed it and now the car is running as it should be.
When fitting the chain, I made sure to get the timing right because I know the m117 is an interference engine, and I was pretty sure I had got it correct. But I guess there was enough play in the cam gears to make it look right, even if it was 1 tooth off.
I had Young Street also change the SLS Accumulators (Air Cells), thinking it would sort out the clunking from the rear suspension, but other than leveling the car a little better, it made no difference. The ball joint on the bottom of the hydro-strut has a bit of play but can that be causing such heavy clunking?
The odometer stopped working last week. Apparently there are little plastic gears that get worn out over time. Probably leave this for an early-winter project.