Stumbles on acceleration

2008 equinox 3.4L stumbles on acceleration but does not set a code. I have replaced plugs, wires, egr valve, air filter and coils not sure what to look at next.

I'd install a fuel pressure gauge and monitor the pressure while it's acting up. Key on engine off pressure should be 56-62psi.

Thanks! I have a pressure guage and I'll check that out. I was going to replace the fuel filter but I'm told that it is non serviceable and that it is in the tank. I don't really understand why they would do that but apparently they did.