560 SEL idles/runs rough and high idle

[nokandolah]

Hi all. I am a newbie and this is my first post. I have lurked and gotten a lot of helpful info from the forum about brakes, oil, general maintenance, etc. but I am now stumped.

I have had my 88 560 sel for three years and has been great until recently. High milage but uses no oil between changes and everything works. The problem(s) are: It starts cold after a couple of revs and runs ok until it reaches temp 80 C. It then starts to idle very roughly and shakes the car. When I drive I can feel the hesitation and sometimes it feels like a headwind. When I idle in neutral with it warmed up it idles at 1000-1100 rpm. The real head scratcher is sometimes it starts and runs and idles with no roughness at all! It is intermittant.

I have done the following after reading a lot of the old archives:
Replaced the OPV
Replaced the fuel pump relay
Replaced the O2 sensor
Set the Lambda to approximately 50%
Replaced the water temperature sensor
Cleaned the ICV with carb cleaner

The problems started about the same time as I replaced the thermostat. Car was extremely slow to warm up. I also had a problem with a fuse when the windshield wipers and front windows won't work. I unplugged and replugged all the ice cube relays and got the electrical function back. Could any of this affect the rough running?

As part of the troubleshooting, when I pull the connector from the ICV, idle jumps up to about 1500. When I unplug the OPV the idle jumps to about 1500. When I unplug the EHA, nothing happens but when I plug it back in the idle drops to 650 and then slowly rises again. I tried pulling the spark plug wires one at a time and could not get any difference. It continues to miss. I also checked all the vacuum lines and sprayed carb cleaner on all the lines and the injectors and got no speed change. Engaging Aircon makes no difference in the roughness.

I have not checked fuel flow or pressure yet. Plugs were new last fall.

I know this is long, but any advise will be persued.
Thanks.