Your 87 does not have a diagnostic, only an O2 sensor light.

Check all your idle air hoses for cracks. If they are hard or have not been replaced by you since owning the car, replace them. Get them from the dealer, not online. Trust me. I replaced all mine with URO aftermarket and they cracked within a year. I had a thread about why my 260E was not starting.

Last time fuel filter was replaced?

Pull back the passenger carpet and probe the O2 sensor connector to see what you are 'really' running for duty cycle. If you receive a slow output, or none at all your O2 sensor could be toast.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k