1994 BMW 325 check engine light and small

The check engine light in my BMW 325i came on last week and although the car seem to be running well, it hesitates a little when it is cold and first driven about a half a block (outside temperatures are in the 20s & 30s). The car travels a very short distance and has never really warmed up since the light came on. There is a new smell that is like a very rich exhaust smell. The car have 89 octane gas in it currently. Should I tow it to the repair shop or run it until it warms up completely?