I was driving home from wallyworld a few minutes ago when the check engine light went on. I stopped, looked under the hood....nothing amiss. Shut off the engine, disconnected the battery, reconnected the battery, started the engine.....now the light is on continuously.......drove slowly home.....light goes back to flashing after a couple of miles.......I can't find anything that tells me what it means/why it would change......help please

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85 380SE Bertha 352000+ miles