Getting a Q45 running after it sat for about a year

[gas money]

Hi Everyone,
My wife's 2000 Q45 Anniversary Edition (approx 125,000 miles) has sat untouched for about a year. Before this it sat for 6 months before I started it to move it. I now would like to fix it and sell it but I am seeking advice about what I should do before putting a new battery in and starting it. I thought I could add something to the fuel tank to help with a possible dead gas issue but not sure. Any advice is appreciated!

The sitting all started because the car was overheating during normal driving conditions. This problem came and went and came back again, which I don't understand. I replaced the thermostat but that didn't solve the problem. This car is my wife's old car so I don't know everything about it's history, unfortunately. When the car was her daily driver, I noticed that there was some white-ish smoke coming from the tailpipe, but not much except under hard accelleration. This makes me think it needs a head gasket (please God no!!), but an Infiniti tech almost wouldn't believe that a Q would have head gasket problems when I called him. I have asked her if this car has ever overheated badly (not just got towards hot on the gauge) and she told me no, but who knows.

Another problem that this car has is a weird vibration when braking- the shifter moves back and forth (forward and backward) as if a transmission mount is broken or something is loose in the drivetrain. I have always done my own brakes and this is not a warped rotors kind of vibration. The car accellerated and coasted smoothly; this is only under braking.

Thanks for taking the time to check out my post. If you guys have any experience with any of this or any advice, please post!

[maxnix]

If the tank was not full when you parked it and you used no gas preservative, I would drain the tank to avoid any issues with condensation or varnish.

Water pump?

125K on a FGY33 is nothing if properly maintained.

[gas money]

Yeah, I was thinking it might be best to just drain the tank. I will check the water pump.

I hope it was well maintained, but I really don't know the car's history. My wife was the second owner, and I don't know how she treated the car before I met her! As long as the head gasket is ok, I feel like the car is in good enough shape to fix up. The car has a nice ride as far as I can tell, but I plan on checking underneath to see if it has had new struts and what that crazy vibration is. I spent several days reading on the forum before I posted and it looks like there is a lot of good information on here!

Thanks for the advice.