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!