Stalling 740 wagon.

I went to pick up a car that I bought online yesterday and was very surprised by a sudden stalling problem during the test drive. First of all, the car`s info:

-1990 740 Turbo wagon
-automatic
-228k miles
-good body
-mechanically in pretty good shape
-doesn`t smoke, makes good power
-voltmeter reading okay
-temp gauge just over half at operating temp


While driving the car in city traffic, the car suddenly stalled while waiting for a light. No warning, no obvious reason. The car actually continued to stall for no reason about
once every 6 or so stops. It idles perfectly at a stop and then suddenly dies (feels like a car cutting out when the battery connections fall off or become loose- checked those though and they are tight). It doesn`t matter if I have my foot on the brake or not. Then the car starts with no problem after waiting about 10 seconds.

Since this car (would be) my first Volvo and since it has a lot of miles on it, I am a bit worried about this problem. I have had a lot of VWs and BMWs and have a pretty decent idea about
the mechanics involved, but am a bit stumped.

Also, the car seems to be leaking oil (perhaps forcing it out of) the oil fill cap on the valve cover- not sure if this is related, but it struck me as odd.

Any ideas?

Should I run in the other direction as fast as I can ? (the car is pretty cheap (750 bucks) and would be a good daily driver in good general shape if not for the stalling)

Thanks very much in advance.

Denkikun