2003 Kia Spectra

Engine Performance problem
2003 Kia Spectra 4 cyl Two Wheel Drive Automatic 60000 miles

2003 Kia Spectra-
Randomly misfire on cylinder #1 verified by pulling p0301 as well as p0300 p0302. Spark plug #1 is wet, and is firing. Swapped coil packs to verify. Problem remains in #1. Swapped injector 1 and 3 problem remained in cylinder #1. Compression test verified all cylinders have 150 psi. Cylinder leak down no obvious indications of a problem. When I start it for the first time or after it sits for 5 ten minutes it will run just fine it’s when I put a load on the car is when it starts to misfire and doesn’t recover until it sits for a while. Lost on what to do next.
October 19, 2010.

Have you checked to make sure the injector is getting continuous power?

Yes as it is misfiring the injector is still operating electrically and mechanically. I put injection cleaner in the cylinder let it sit for a while and tried to clean up some of the carbon, because when the car starts to misfire (under load) it pings pretty loud so I naturally suspected detonation/pre-ignition. Yet this problem still persist to be annoying

Oct 20, 2010.
Have you checked the knock sensor? Here is the test procedure. I was able to dig it up for you.

Disconnect the sensor electrical connector.
Remove the sensor from the engine.
Mount the sensor in the jaws of a bench vise.
Connect a voltmeter between terminal 1 and 2.
Wrap the bench vise sharply with a hammer and note the voltmeter reading.
Verify that the voltage spike is less than 1 volt.
If no voltage spike is observed, replace the sensor.

NOTE: You need to remove the intake support bracket to access it.

Let me know. It plays with the timing and can cause the noise under a load, so it's worth checking.