this is my first ever 1991 300zx non turbo and im having acceleration and idleing problems. i have changed my spark plugs,ignition coil packs,feul filter, and my air intake. i have talk to several different people and have got several different answers. some say air control valve, some say fuel injecters, and some say that i need to fix the timing. what happens is when im driving the car out of first gear it acts like it wants to stall and if im pressing the peddle to the floor i get no acceleration like its not getting any air or gas but i dont know at all, can someone help me out?

you need to run the ECU codes (google "300zx self diagnostics" to figure out how to do that). if you get a 55 (all good), then check your fuel pressure. also, look up in the online fsm (first link if you google "300zx fsm") how to test your MAF and do that.

^ That, and did you ever test your injectors?

I had pretty much the same exact thing happen with my 90 N/A. I ended up changing my fuel filter, spark plugs, a coil pack, alternator, battery. But in the end i did a little research and it was the PTU (Power Transistor Unit). If that's the case just bring it to any Nissan dealer and they will replace it at no cost, since it is an open recall on the part. You can call them and give them your VIN# and they will let you know if it has been done before. Im not saying this is exactly whats wrong with your car, but it sounds very similar to the issue i was having except mine got worse and actually started stalling out. Hope this helps.

knock sensor, code 34. saftey boost retards the timing'I have one on order right now for the same issues.

^ I hope you ordered the harness, too. More often than not, the harness is the cause of the code 34, not the sensor itself.

They will only replace it if you have an OLD style PTU and it has never been done before (IE if you have a new style PTU, and it's failed, they won't replace it for free).

your timing can jump and cause this as well. but if this is the case, it has only jumped one tooth (still needs to be fixed), when you get more than a 1 tooth jump, your car will run like poop, and shouldn't be driven (hell, it shouldn't be driven with even a 1 tooth jump).

relocate the knock sensor for future problems that might involve it so it's easier to get too.

how do i test the injectors without takeing them out. or do i have to remove them?

No you dont have to remove them just take off the plugs (Be careful, if they are brittle they can break easily when removing the metal clips) Then test the injectors with a multimeter. It should read about 13.

what would be the name of that harness and where can i find the harness on my car?

... it's the connectors that connect to the injectors. This isn't quantum information science...