Car should run just fine on 87 octane, unless the PCM has been tuned for premium. Is the car all stock? Mileage? Post your car make model, recent maintenance items replaced, and symptoms in the maintenance section and you'll get some responses as to what it could be.
I tried switching to 87 from 93 on my under 30k ss a few thousand miles ago after reading that im throwing my money away with high test, and i didnt like it. I can't recall exactly why, but i think it had somethin to do with a hesitation and also engine noise.