revving problem
 

Ok, so here's my problem:

When I start my car, the 83 ZX, I'll slip it into neutral and rev the engine a little bit. When I do, or attempt to, the engine's rpm's will drop significantly, and sounds as though the engine is about to die. Then, after a few moments, the engine will rev properly and the rpm's will rise. What could possibly be the problem? If you could, please email me at rockyrutter@hotmail.com with a repsonse, but a simple reply to this post would still be greatly appreciated. Thanks!

you might have a vacuume leak somewhere or your AFM is starting to go out.. i just recently had to change mine.. and i was having the same problem with mine before it totaly craped out on me and after changing it that problem went away..

boot
 

most likly your AFM boot check it i had exact same prob and it was pissin me off i changed my boot and now its good....:)
if its got cracks or holes in it that will affect it

Sounds like its starving for fuel ;)

Take off the sender line too the fuel rail crank the car over and you should be getting fuel through...

Check your fuel filter and re new if old.

Not knowing alot about ZX's thats all i can think off.

AFM?
 

Thanks everyone for your prompt responses, but if you could - what does AFM mean?

Air Flow Meter !!!!!

Its a box like thing your intake mainfold joints onto it :)

Does this only happen the first time you start it in the morning or every time you start it even after driving it for a while?

If its only in the morning, you may have a cold start valve failure or faulty head temp sensor that is telling the computer that the car is warm and won't actuate the cold start valve. Could also be a bad fuel pressure regulator or a fuel pump that is allowing fuel pressure to bleed off when the car is off.

If its only while hot, you may still have a faulty head temp sensor, fuel vaporization due to malfuntioning fuel rail fan, or vaporization due to low fuel pressure. Or any number of things.

I'd start by hooking up fuel pressure guage and see if you're pressure is in spec and if it bleeds off while the car is parked. Always start with the basics.

Distributor?
 

My 280zx was doing the same thing and then it was doing it more and more when I was driving. Eventually it got real bad and I had to pull over and park it, the engine would run but if I gave it gas it would die. The distributor was worn out.