Over the past month or two my 04 sedan has started jumping/shaking while at idle in gear. happens after the car is warm and I am at a stop light or other stops. if I shift into neutral the idle goes up about 100 rpm and it settles down. it also mostly stops if I turn off my a/c. it threw a CEL a couple of days ago, but went off yesterday.
Any idea what it could be?
changed out both cam position sensors about 3 months ago. car is pretty much stock except for a plenum spacer, z tube, and k&n drop in filter, all of them have been on for 4-5 years now.

 

bump...no one?

 

Since you have two of your G35s doing the same thing I would look at where you're buying gas. Sounds like the gas you're using has been contaminated. You did get gas for both of them at the same station? When you throw an error code you need to find out what it is, they can be a key to what's going on. Most autoparts stores will read the error codes for you and let you know what they mean....Gary

 

I have the same problem. Did u try cleaning your throttle body and intake filter? Idle reset?

 

it's only 1 car...in the op I said I changed out both cam position sensors (driver and pass side)

I had reset throttle positions and ecu a couple of times and it didn't help.
replaced air filter recently, mild help but it was short lived. I haven't cleaned throttle body because I've read too many posts about how sensitive it is and manually moving can screw it up.

I changed out the plugs today and so far it seems to be running much better and the jump is gone. from the look of the plugs I think #2 was fouled and might have not been firing, hence the jumping.
#2 also had a little oil in it, but not soaking wet. I am at 108k miles so no warranty work. wish i'd known about the common issue when I got the car and would've kept an eye on it before it was too late.