So, I have a 1982 280zx N/A that is completely stock. I bought the car with a half way done clutch job, so unfortuantely, I've never heard how it is supposed to drive. Ever since I've had it, it has had a really bad miss, but it seems to be at low rpms only. The car doesn't have to be on the road, I can simply hit the gas in neutral and make it miss. I have a video of it I hope it comes through well. The problem goes away if I hit the gas hard enough. (I didn't make a video of this, but I can do that tomorrow if its needed) It has new plugs, wires, and distributor cap. I have also calibrated the AFM with the water test. I also replaced the gaskets for the fuel injectors (completely separate problem that has been solved) I've spent hours, and I mean hours looking for a vacuum leak. I found a couple very small ones, but nothing major. Unless I'm completely missing an area of the engine (which is possible I suppose) then I don't think I have a vacuum leak. I just need some direction. I was thinking maybe the vacuum advance or something? I'm really not sure. I also plan on checking fuel pressure tomorrow. Some direction would be great. If there is anything that I forgot, feel free to ask. Thank you.

 

Have you checked timing?
Read the spark plugs?
Tested all sensors?
Yes... check fuel pressure too.

Check the basics outlined in the FSM...

 

Sorry to be so delayed. I finally figured it out and it turns out the TPS was way off. After adjusting the tps, it runs perfectly fine.

 

You really need to fix the exhaust leak. I am hoping it is because you don't have a muffler, if not replace the exhaust manifold gasket pronto. The leaks will make the engine have very poor power and run not so good.