I have a new ( for me ) 1995 2L 480 ES.
When I bought it, there were problems with a very rough idle and pick up. Most of this was solved by fixing the ground wire on the MAP sensor.
After that the car acted the same way as a carburator engine where the vacuum hose on the distributor is disconnected: hesitation on pick up.
Measurements from the Lambda (oxygen) sensor were reading between .27V and .7V
with about a 1 second cycle.
I replaced the Lambda today.
Total performance seems to be improved, except for the hesitation at pick-up and rough idle when the engine is warm.
I suspect the idle control valve and temperature sensor.
The temp sensor seems to be under plug #1 (according to various 480 forums)
But where is the idle control valve and sensor?
Any info, advice and/or comments would be welcome.

you could check all the vacuum hoses for blockages etc, the idle control valve I think depends on the engine, on some it will be in the fuel injector, in others its (I believe) on the front of the engine, about half way along (you can tell of you disconnect it the engine runs badly or stops, I;m not really sure as the latest version I have had is the 91 440., but to be honest any of the sensors mis reporting can cause similar problems, have you pulled the engine codes yet, they will give more info.
Grendel

Thanks grendel1960.
The engine codes (even before the lambda change) come up 1-1-1
I haven't measure the signal on the new sensor yet and I'll check the resistance on the temperature sensor today. I've just re-installed VADIS on an old computer and want to check what info I can find there.
Anymore ideas, anyone?