Ok I'm going to ask the board what my problem is:
Ready? Here we go!
I got my 81 280ZX N/A running this weekend (enter applause) and it's running like a top. However I have a small driveability problem at partial throttle. It idles good and rev's fine, but when you drive it and hold the gas at say 2800 rpm's it runs and the falls then does this over and over untill you either let off or get on the gas. I can just rev it up sitting still and it will fluxuate from 2800 down to 1500 and then right back up. I am thinking TPS but thought I would ask before I replace it. What do YA'LL think?

 

Mine does this as well. I've cleaned contacts and connectors, but the problem persists. Doesn't much affect me though, since I mostly drive with my foot to the floor.

 

I had the same problem for a while too. Is your car running at full power when you get on it, or does it feel like it's missing a little oomph? I'm trying to remember what I did to fix my problem. I can tell you it was definitely an electrical malfunction in my case. I just can't remember what exactly it was. I've had to replace so many damn parts on my Z it's getting hard to keep track of what fixed what.
Kind of sounds like it's getting choked off at part throttle, like enough air ain't getting through. The Haynes manual describes how to check your TPS with an ohmeter if you got one or know somebody who does. Also check the door to your Air flow Meter. It has a bypass at idle but at part throttle it might not be operating properly. It works on the same resistance principle as the TPS. It uses resistance for the cpu to determine how far the door is open. If it's reading wrong then you can run rich or lean. Each setting has it's own electical contact on the bottom. Check for corrosion there. The haynes manual describes the testing procedure for this as well.

 

Oh yeah. If you got a 280zx then you might as well invest in a multimeter. These cars can have a lot of electrical problems. Mainly due to age. Just an afterthought to my post above.

 

Hum almost sounds like an idle isue. I wounder if ther is a flat spot in your tps? if you had a scope you could finde out. A DMM is not fast enough to catch a flat spot in a tps.

 

It is the TPS! I unpluged it and drove it down the road with no problem then swapped it out for another one I had. Problem solved. I also checked the contacts first but the were making contact. Also I do own a multimeter My first Z was an 82 back in 1995 Been there and still doing that. Thanks for the responses.