I keep getting a p0304 code, What should check?

Question

I have a 1996 ford windstar, I am trying to smog it, and code p0304, keeps coming up. I have done everything, changed plugs wires etc.. it runs great! what do I do?

Answer 1

have you check/replaced the injector? I would use 91 octane from Shell and use a good fuel system cleaner and maybe do an intake flush