RPMs jump, MPH doesn't, engine shakes, HELP

[drc4423]

2003 g35, car only has 60,000 miles on, previous owner kept really good care of it, but recently when driving and hitting the gas the rpms jump, but the mphs aren't catching up and when it hits 40mph the speed just stays. Even when you press the gas as hard as you can the engine revs but nothing happens, the front of the car shakes and jolts a little bit. You have to let go of the gas pedal and keep trying. Seems like the gas isn't reaching the whole engine, too much oxygen, computer chip problem? Anyone else have this problem?

[Infinitiguy19]

Any Check Engine Light codes?

[drc4423]

the check engine light did come on, but we took it to the dealership and they tested the codes and now its off, but the problem is still happening. They wanted to replace the whole transmission, and i said no way, getting someone else to look at it, so now I'm stuck.

[zozoka1212]

I assume you have AT. What was the code? That's one thing they cleared the code but they should tell you what the code was.