Adjustable FPR for '96 S10 2.2L?

I have a question that I'm hoping someone will know the answer to: Can I get an adjustable fuel pressure regulator for my '96 S10 2.2L? It won't pass smog because it keeps setting code P0172(System running too rich bank 1). Since every other option that I've explored has failed, I'm hoping to mount an adjustable fuel pressure regulator to the fuel rail and set it to the proper operating pressure. Or to whatever pressure allows the engine to run correctly. Any input anyone can give me about this will be greatly appreciated!