Im trying to test all the ignition coils on my 1990 300zx na 5spd. There all mounted but unpluged probing the left and middle im reading 0 on all of them? Am i doing something wrong or are they all bad? It runs but not very good and when i run it and unplug each one one at a time #3 #2 and #6 are the only ones that make the cars idle dip down almost dieing when unpluged. I also checked each injector for resistance and all 6 are at 1.1ohms. The only code i have is 13 for the coolant temp sensor which ive tried two brand new ones but still getting code 13. Any help or advice would be greatly appreciated thank you.

Yes something with your testing is wrong. Ignition coils in my experience are almost never the issue. It's usually PTU related or dead injectors so I would check the PTU/wiring as well. As for your coolant temp sensor check the plug for corrosion as well as your wiring. Try unplugging the battery to clear the code then drive around for a bit to see if it comes back.