300zx won't idle

My 1990 300zx will only stay on while I’m holding the gas. If I let go the RPMs will drop and the car will die. It revs fine and everything, but won’t even try to idle.

Is the maintenance up to date, air filter, gas filter, plugs etc?

Depending on the flavor of the fuel injection, there is an idle-air control solenoid that pretty much controls idle speed…If the EGR valve is stuck open, the engine will not idle…Any large vacuum leak will kill the idle…