Hi Beagle,
Answers to your questions:
1. Compression test was done about 12000 miles ago,readings between 300psi and 325psi all cylinders. Fuel and fuel filters don't seem to be an issue.

2. The rough idle is along with a slight hunting.
When loosening the injector feed pipes one at a time each cylinder would drop out the same and recover when tightened again.

Could be pump calibration I guess. 280000 miles on the car and no pump service done in the last 200000 miles have owned it.

I have to look again but I don't recall seeing the linkage shock absorber you mentioned.

I also have to double check the two adjustment screws and the spring for the idle stop.

I guess I will also check the compression again since it's possible something happened in the last 6 months.

Thanks for your reply.