BMW Repair: 89 735i blown head gasket?, blown head gasket, water coolant

Question
my 89 735i had what appeared to be oil in the coolant resevoir.
The car severely overheated 6 mo. ago due to a cracked coolant
resevoir (lost coolant).  The engine has been running very well
but a week go began to miss and act like it wasn't getting gas.
Checked the resevoir and it looked like chocolate milk( first time
I've checked it since replacing res.).  Replaced coolant, but
overheated because there was air in the system. Corrected that
problem, then a few days later, car began running rough and
"check engine" light came on.  Drove it about 3 miles like that.
could this be a blown head gasket & do you think it may have
caused engine damage. I drained the coolent and ol from the car
because I didn't want water & coolant sitting in engine. Recent
repairs: O2 sensor, platinum plugs, oil change (from synthetic to
10w30). Car has 130k miles. Also, my husband has successfully
replace heads in other type of cars, but was wondering if BMWs
ppresent exceptional difficulties.

Answer
By what you have described I would have to say it is either a head gasket or a cracked head.Hopefully just the gasket.It needs to be torn down and checked.Have the head pressure tested for cracks and for flatness.It isn't a hard job just alot of time and the money could be extreme if it ends up being a head.Its about 9 hours for a head gasket( not counting the machine work)and twice that if you have to replace the head.