I have a 2004 G35s. So recently replaced the clutch about a week ago. Now for some reason as I am driving the car. It starts to feel like the brakes are being pressed rapidly or maybe more like the fuel pedal is being pressed and released repeatedly. Like a studder from poor fuel delivery. I know that it’s not drive train or brake related. Also I notice that it only happens when the fuel pedal is held at a consistent speed for about 20 seconds or so. Then if I keep on working gas pedal up and down it doesn’t do it at all. So I am thinking that it is fuel related, perhaps water in fuel, bad fuel, fuel filter or pump or maybe injectors? Has anyone else experienced this??? Or know where I should start my trouble shooting.