1989 Pontiac Firebird Car is gutless

Bought the car last year. Replaced the fuel tank and pump, had the fuel injectors removed and "rebuilt", new spark plugs and wires, made the cool air intake larger, k&n filter, and even after all that, the car is gutless. Is the v6 engine too small for this vehicle?

Someone told me that it is possible that the cars performance was decreased. If you go into the diagnostics, you can "turn down" the vehicle so the car is more of a "freeway driver" instead of a "street racer". Is that true? Is it possible to do that? If so, how do I "undo" it?

Thanks for the help