OK I have a problem with my 91 honda civic it's a 1.6 lt engine and I have an issue with it topping out at 3000 rpms. I have already replaced the distributor cap, rotor, ignition coil, pcv valve, fuel filter, fuel pump, and O2 sensor but it still keeps topping out at 3000 rpms. What could it be?

Replace the Ignition Control Module:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-4.html#post265896

OK thanks a lot!!