Hello all.
After a head gasket change / head refurbishing and replacing thermostat and some coolant pipes, my car now runs very well in the road but it tends to have a very low idle (about 500-600 rpm) and stalls occasionally on stops. It gets even worse when a heavy electrical load like headlights are connected.
It didn't idle so bad before, so what do you guys think can happen?

It is a 190E 2.3 8v (1992)

Thanks!

To give a bit more info:
Yesterday I observed that the car starts ok, does the high-idle sequence (1000-1500 rpm) ok, then idles ok (about 800 rpm) but as time passes, idle is getting lower and lower (car runs perfect). It is not related to engine coolant temp, as the car cycled from 80 to 100 deg several times but the idle reduction was constant. The exterior temp was 13 degree. When the car was running for about 20 mins, the idle was so low that I couldn't let the car idle because it stalled just every time.

Does this give any clue?

In the posts several stalling problems are said to be related to the fuel pump relay, but I think this is not the case with my car as it is progressive and the car runs fine without hesitations, etc. The fuel pump is noise, that's true. But a fuel starvation should manifest in the normal running, not only the idle, is that true?

Thanks!

I think the problem is solved.
Just in case this is useful to others:
After looking at the duty-cycle reading in the X11 diagnostics connector with a portable oscilloscope, looking for a incorrect mixture setting, I found it to be a bit rich, so I corrected it.
However, I don't think that was the cause, as I also found that the mixture didn't change when the car idled with respect to low (1000rpm or so) speed, so I suspected the idle microswitch.
And voila! I found that it wasn't operated by the throotle cable lever, so when I pressed the microswitch just a bit the duty-cycle and hence the engine speed changed (I could easily hear the "click"). So I adjusted the nut of the cable and now it operates it.

I have been running for a while without problems, but I will confirm that it is solved tomorrow, when I go to work.

I'll keep you posted.