I have an 03 350z, I have been having issues with it sometimes struggling to start and when it does start the RPM gauge goes crazy, while I'm driving it it has less of power and the RPM gauge jumps around a lot. I read some forums found that it was the Crankshaft Position Sensor, so I replaced it last night. However, this morning after driving to work i went to start it again and it struggled, then didn't read the RPMs at all, the gauge stayed at 0 and once it started working it was jumping all over the place again. Any suggestions on what I should check next?