the window issue is because it is putting a load on the engine,even if the windows are all the way up and you are idling,try holding all the window switches up at the same time and it will strain a bit. All cars will do this. As far as the belts being to tight,if you overtighten the belts on a VQ35 it will cause the engine to sound like it is knocking due to so much pressure being put on the front of the crankshaft.

 

most of the idling issues with these cars are normally due to them having trash or debris in the mass air flow sensor,or the fact that they need an idle air volume relearn procedure performed,also check the little hose that hooks to the intake tube at the throttle body,i have seen people leave this hose unhooked when messing around with air filter boxes and removing intake tube..hope this helps guys

 

^^What would cause a car to need an idle air relearn? Can this issue just pop up randomly or is it normally caused when people do something to their car?

 

Or you know what, this may sound sort of dumb but, are you sure your MAF is plugged in?

I remember once on an installation I forgot my MAF sensor and my car was idling all crazy with lights and I couldn't figure it out for a few hours.


And the Idle Relearn thing is only due to the cleaning of the throttle body. If I'm right, when you touch the butterfly valve, it completely throws off the calibration.

 

Spark plugs? But it on;y has 82K so most likely not

 

I'm going to check all the things you guys recommended. Could it be that the alternator is dying?

 

Anything is possible, but in the 7 years I've been with Infiniti I have only replaced 2 alternators on the VQ35 and one of those was due to a noise internally. Anytime you change plugs,clean the throttle body, or do a fuel injection service a idle air volume relearn procedure should be done...