2000 Kia Spectra

p301 isn't a complete code. All OBD-II compliant codes are a letter
followed by 4 digits.

Pull the plug for the #1 cylinder and look at the electrode. If it's
covered in sooty black deposits then it is likely overfueling due to a
bad fuel injector. If it appears normal then suspect an ignition
problem. I've not worked on the 2000 spectra, does it have a
distributor? Possible items are the distributor cap, if it has coil
packs then you could have a problem there.

How old are the plug wires? I've seen perfect looking plug wires be bad
due to a fault in the rubber portion that extends down into the
cylinder head. Another possibility is a spark plug with a cracked
porcelain section. If you cracked it during installation it can allow
that cylinder to misfire to the head instead of firing the plug.

Chris

Check that the throttle position sensor is operating correctly, and no
debris has gotten on the contact. This would not necessarily generate a
code, but would give you a rough idle. Clean off the contact on the oxygen
sensor also. If you live in the North East, the nice people who rip us off
for fuel, had added Ethenol to the fuel. Try running a good fuel injector
cleaner with Methanol in it, or have a mechanic do an isolated fuel
injector cleaning. My mechanic just disconnected the fuel pump fuse, and
put a small pressurized tank full of clean gas and methanol and injector
cleaner, through the injectors. Made a world of diffrence. My misfire was
from bad gas that showed up all over the New York area one week. The poor
quality of the fuel causes the computer to try to corrct the problem, and
it does this by retarding the timing, i.e., rough idle, and runs hotter.

i have the same problem and the solutios is the fuel pump, the pressure correct is arround 5psi check that all messure lower is  a problem

Kia repair shop says its a faulty ground in the TPS system or the TPS has been adjusted. $80 if ground problem repair and $150 if TPS adjustment and ground repair

2002 kia spectra electrical problem

I had the same exact problem and it was the computer.
I removed it, opened it up and there was a black spot that was melted. New computer fixed it. You can get them cheap on ebay.