Its a 1992 300ZX N/A, 2DR.

Well..Two days ago i cleaned the K&N Air filters, and changed all plugs, since then the car doesn't wanna keep a steady idle, miss fires more then it did, doesn't feel like its putting out the power it should be putting out when pressing the gas while driving, and sometimes while driving the car just dies out, and i gotta turn the key or put it in gear and let out the clutch for it to turn it back on..what could be causing this? Does any1 have any related problems?

Earlier this morning i took out the coils, and checked all the spark plugs, 3 of them were really really black..like very bad, something that shouldn't be done to a plug within a few miles of driving. And they were a lot worse then the ones that were in the car when i did the change 2 days ago..The other 3 were dirty, but not as bad as the other 3. Also when you press the throttle u can hear like a "suck" of air somewhere..looked at all vacuum hoses, but don't see anything missing or disconnected.

If you changed all the plugs then you had to remove the balance tube and a few other vacuum lines, right? Did you reseal the balance tube to the plenum? Did you accidentally put the bracket UNDER the balance tube on the pass side? Check all your vacuum tubes and clamps and make sure it got put back together right.

Assuming, of course, that it ran just fine before you changed the plugs and you were just doing PM....

you said you messed w the filters right? did you disconnect the MAF harness and forget to reconnect it? dont ask why i would think of that -.-

The MAF is connected, and the balance tube is sealed down right, with the brackets sitting over the tube, i checked the vacuum hoses near the balance tube and everything is connected..I'm starting to come to a conclusion that its my coil packs..is there a good way i can diagnose these?

Don't know how to check coil packs, but do you know that all your injectors are good?

I don't have a way of diagnosing them, but Well today on a 70 Mile drive, my 1992 Nissan 300zx N/A burned approx. 8-9 Gallons of gas..I know its misfiring, but i don't know where to start on diagnosing that. It likes to randomly shut off sometimes while driving too, just the motor though, not anything electrical. Also at time, you can smell string exhaust fumes from inside of the car.

Injectors can be checked a couple ways, but mainly by checking the ohms, should be around 11-14 ohms at the open connector (but maybe you don't have an ohmmeter). But, yeah, sounds like you got gas. No ECU codes?

I'm wondering if the connections to your coil packs are intact, were any of them brittle or broken when you changed your plugs? What you need is a working set of coil packs that you can borrow from someone in the area to see if that's the problem.

Ima ohm test the injectors soon..also the coil pack wires have a few minor breaks in some spots..I was thinking of buying new wire ends..cutting them off the wiring harness then soldering on new ones and see if that helps

Alright i got news.

Well i replaced the Coolant Temp Sensor, but he computer is still giving me a code 13, do i have to reset the computer somehow then re do the diagnostics or what?

I also OHM tested my injectors and coil packs Here are the results.

Injectors

Cylinder 1 - 13.2
Cylinder 2 - 13.5
Cylinder 3 - 13.5
Cylinder 4 - 40.1
Cylinder 5 - 13.2
Cylinder 6 - 40.6

Coil Packs (my 0.4 resistance from the meter is already subtracted)

Cylinder 1 - 0.8
Cylinder 2 - 0.8
Cylinder 3 - 0.7
Cylinder 4 - 0.8
Cylinder 5 - 0.8
Cylinder 6 - 0.8

I'm guessing cylinder 4 and 6 injectors are bad..since i heard that they should normally be ranged around 11 - 13 Ohms, and those 2 hit 40. Coil packs seem to be good, they're supposed to Ohm somewhere around 0.7 - 1.6.

Well I think your best bet might be to replace all 6 injectors with replacement ones from http://www.deatschwerks.com/ they sell a new stile injector with an adaptor kit to use with the old stile fuel rail. It also includes all new injector plugs too. New stile injectors are less prone to failure with ethanol based fuels so if you plan on keeping your Z for years to come then this would be a more permanent fix instead of just installing some used injectors. I might also recommend that you replace your O2 sensors while you are at it. In regards to code 13 what sensor on the water pipes did you replace? The 2 prong sensor for the AUX fan in front of the AC condenser the single prong one just tells your computer and temp gauge how hot your engine is. If you un hook your battery for about 5 min and code 13 fails to go away check the sensor plug. I don’t think you have anything to worry about with the coil packs. I hardly ever see them go bad. Normally the clips brake from age and dry rot and I have remove a few broken coil packs that look like someone tried to install them with a sledge hammer .LOL Hope this can help you get your Z back up and running. Let me know if you need any more help but please forgive me if I don’t get back to you in a timely manner I am in Afghanistan still have a few months left before I head back state side. Take it easy – Tony

Hey Tony, hope you're doing well. Keep safe, buddy!