KA24DE trouble

[Ace]

My stock KA24DE motors check engine light came on the other night. The car ran fine but a few nights later the car seemed like it was going to die at idle and would drop from 700 rpms to 300 rpms and then bounce back up. Also once I took off it would seem like it was not delivering enough fuel. So I replaced the fuel filter because I haven't had the car but two weeks. The car is running better and I haven't really had the problem again. But the engine light is still on. I suspect the oxygen sensor, but I'm not sure. Does anyone have any suggestions to the problem.

[Nis240sanSX]

I don't know if you have AutoZone's in WA. but here, you can take your car to Autozone and they will check the codes on your ecu and tell you what is wrong for FREE. If you can't do that, you can go to 240sx.org and look at the FAQ and it will tell you how to take out your ecu and check the codes yourself, I did mine TONIGHT, it wasn't that hard, it took me about 45 min. to do.