I have a 2003 350z with 100k miles. Sometimes in 2nd or 3rd ill hit the gas and I can even put the pedal to the floor and the car accelerates very very slowly. At first I thought it was my clutch slipping as the guy who repainted my car said he noticed wear when working on the car and I had my mechanic replace the clutch and flywheel.

I realized afterwards that it couldn't have been the clutch because the RPMs also go up slowly when attempting to quickly accelerate. This issue doesn't always occur. I took it back to my mechanic to get a diagnosis but he was unable to figure out what it was and thought it might be a computer based issue and recommended taking it to a Nissan specialist as he can only get the basic codes and not the same info as the dealer can.

He thought it may be related to the ABS system. Has anyone heard of anything like this? The only place I can think of taking it at this point is my local dealer but I hate getting overcharged there.