start at the engine, where the fuel enters the injector rail, then follow the hose, through all the filters & pumps (not sure if a 300zx has an external or internal fuel pump) & continue all the way back to th fuel tank, look for seepages, & wet spots on the fuel line.
air flow is bad or t.p.s is bad check spark, check fuel
Craigslist is a good place to find used vehicles such as the Nissan 300zx Twin Turbo. You can also check the SuperPages or YellowPages online for more options of where to buy the vehicle.
check vacuum lines top passenger side rear of engine
check your idle control valve located behind the engine
no fuel to the injectors check fuel filter or replace check fuel pump see if it's working check relay
http://www.300zx-twinturbo.com/cgi-bin/manual.cgi Check out this link. I use this for everything when I work on my 300zx. This exact link will take you right to the section that gives step by step instructions on how to replace the oil pan gasket. Good Luck
Check the alignment of your pully and also look for a cracked or broken pully.
Check the crank position sensor
start with 3 quarts then crank it. Let it run for 30 seconds and kill it. Then check the dip stick and see how much you need to add.
Check out 300zxclub.com
check all your battery connections and battery, then check your starter wire. mine was lose and the car wouldn't turn over my dad pushed it in while i was trying to start it and it cranked right up
Look carefully under your hood. There will be a cap with a picture of the wiper blade swipe pattern. If you still can't find it, check your owner's manual.