#1 had a hard caked deposit.
I checked compression on that cylinder and it read: 180 psi and stayed there until I bled it.
I put a new spark plug at it came back fouled a day later. It had what looked to be oil.

1. I don't think it's the piston ring since the pressure held
2. I suspect a valve guide or valve stem seal
3. This must have contributed to my illusive stalling for sure.

Ah, let's not forget, this is a 1988 190E 2.3 8V.

I am now at a crossroad:
1. Should I do a complete head job?
2. Just replace the steam seal and pray that would do it.
What are your thoughts?