1990 Z32 NA HELP!

[brian300zx]

So I've been going back and fourth with this car since I got it no surprise. The computer seems to be playing games with me. At first I thought it needed an o2 sensor then that code went away, gave me a coolant temp sensor code got the sensor, then it gave me an injector code that went away, now we are back to code 13... temp sensor even tho it's new? I cleaned the connection and still gives me the code. Car has massive hesitation under 3k, horrible gad mileage. What else can I do every time I think I find the problem turns out to be something else lol

[NolimitZ32]

Check the FSM troubleshooting section, sounds to me like you may have a bag ground or pin at the ECU

[brian300zx]

What would you recommend looking under?

[NolimitZ32]

the troubleshooting section, its arranged by trouble code.

[DCaff300ZX]

Also, your symptoms are exactly how my TT went before first having to replace the IACV and all of it's connectors, then later the PTU harness as those connectors were too badly corrosion damaged, apparently.
Do use the FSM for troubleshooting your particular problem(s), it will get you going in the right direction and at worst give you some detailed questions to ask here.