Re: tickover erratic on my 164
Often, a poor tickover after an overheat is an indication of a blown head gasket. How hot did it get? Was it really right up to the end of the gauge?
Is the car loosing coolant?
Is there any sign of a thin film of oil or white frothy scum in the coolant header tank?
Is the oil level going UP rather than down?
Is there white gunge under the oil filler cap or on the dipstick?
These are all signs that would also suggest (but not necessarily confirm) head hasket trouble.
Also have a look at all the air hoses round the back of the plenum to see if any are split or collapsed (and the big one from the airflow meter to the plenum). A poor idle can sometimes be down to an air leak.
Is it a 12 or 24 valve?