It's obvious from your description that the engine is getting too much fuel. This could be caused by any number of things. I would start by checking the ECMs ability to monitor its various systems, since you say there is no Check Engine light. This could be something as simple as a faulty bulb, damaged wiring, or even a missing bulb.

Have you owned the car long? Did the Check Engine light ever work before?

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1989 300 SEL that mostly works, but needs TLC