Cylinder misfire on 2006 Hyundai Tiburon

My 6th cylinder is misfiring and I don't know why. I have replaced the spark plug, plug wires, coil pack, and fuel injector and it's still misfiring. I have had it looked at by a mechanic and he told me that before the cylinder misfires there is power going to the cylinder, however after it starts to misfire it loses all power going to that cylinder. I can let the car sit for a little bit and start it up and it will run fine, as soon as I start driving and making it work that's when it misfires. What do I do? Code that comes up is P0306 I believe.

Asked by for the 2006 Hyundai Tiburon
Possible valve train problem best left to an experienced Hyundai dealer/tech?
How expensive is that to fix?
1 more answer , 6 more comments
I'm unsure what he means by "power going to the cylinder." Is it to the injector, the plug, or both? Did the #6 plug look any different than the others? (bright white, black and sooty, wet with fuel?)
I agree with your question , but the part that got me was that it initially starts up and idles (runs) good until its' put in drive , that's when the variable valve timing or variable cylinder management (I work on Hondas) comes into play. Monitoring with a suitable scanner would verify function. A simple vacuum guage could also confirm valve problem as opposed to ignition or fuel related misfire.
At this point, I'm not sure how helpful any of us will be until we know which component is losing power. What's dropping out, the injector or the coil? First thing I would do is let it do its thing for a minute then pull #6 spark plug and see what it looks like. It may have a mashed but not completely shorted wire to coil or injector that only drops out when the insulation is hot and soft. More likely than that, it may have a pin in the coil or injector connector (or pcm connector or any intermediated connector between them) that has lost tension and as it expands from heat, loses contact or creates too much resistance under load. In the past, I have seen problems with the Hyundais and Kias with crimp splice points developing resistance. The coil and injector circuits are usually crimp spliced 6 into 1 or 3 into 1 for power supply and each component has its own signal or ground control wire to the pcm. I have seen them drop as much as 6 volts at the splice and the only way to cure it is to solder that splice. It may also have partially broken wire near a turnout on the harness. With heat comes resistance and increased load has higher demand for circuit integrity. It could even be an injector driver in the pcm but that is highly unlikely. I'm afraid this may be one of those problems that is just incredibly hard to find.
I hope they post the fix/cause for this ..I'm curious.
Still in the process of finding the problem to fix but as soon as I do have an answer I will be sure to post it back on here. I had a dealership tell me it could be my catalytic converter so we will see.
unlikely , for a single cylinder misfire.good luck.
I have to agree. There's no way a bad cat could cause a single misfire. However, the misfire can definitely kill the cat. meow