BMW Repair: driving and shutting off, dynamic stability control, octane rating

Question
i have a 1992 BMW 325i its a 5 speed standard and when i drive the check engine light comes on and it says in the manual its emissions related (O2 sensor and Catalytic converter) for some reason it seems like when it comes on when i drive the engine shuts down and turns back on but it constantly does it i was wondering if this was because i didn't put premium gas in it i put the cheap crappy stuff in it like 86, 87 octane, i didn't realize the manual says only use premium, and also theres a light in between the tach meter and the mph meter it looks like a triangle with an explanation point in it with a circle going around it no manual says what it means i even went to BMW in North Haven and they didn't no what it meant (some help they were) but when that light comes on it does the same thing the engine shuts down then turns back on and continues driving i was hoping you could help me out a little bit hopefully tell me what that weird light means  

Answer
John, the light is a DSC (dynamic stability control light) The only problem is that your car doesn't have DSC. I don't even know if you car had the predecessor ASC system which would close the secondary throttle cutting engine power when the wheel speed sensors detected wheel slip (traction control). If your car is misfiring under load the knock sensor may be telling the DME (engine computer) to reduce load because of the detonation due to the gasoline not having a high enough octane rating. I would use the premium gas if recommended and maybe run a Techron based fuel system cleaner bottle and see what that does. As you can see I am no well versed in the older cars so I am reluctant to give advise.
-Evan