I have read a few of the other forums regarding misfire and took steps to correct the problem and have spent over $100 in parts not getting anywhere! I have a 2001 Kia Sportage 4WD Manual and it has never done anything like this till i started it one day. I checked the flashing CEL light. Code scanner made by Solaris only finds the obvious. Misfire Cylinders 2 and 3. There's nothing else. I've replaced the spark plugs, the plug wires, The Coil pack which controls those two cylinders, the Crank Positioning Sensor. I'm fresh out of ideas. Nothing has changed. It runs no differently when I unplug the first coil pack which controls 2+3. I'm not a full blown auto mechanic ASE Cert, but I've got 3 years w/ Sears Auto, A little exp at a chevy dealer. I'm baffled. I'm about ready to tow it an hour to a Kia Dealer!
I don't think the Cat is clogged, yet, lol. Because you can hear the interval of the cylinders missing. actually, i'm suprised it even runs on two, but whats better than that is that if I unplug #1, it runs on ONE at about 300 rpm is sounds like.. lol. anyway. I can't figure it out. need transportation soon!
p.s. I don't think the fuel is in question. The exaust downpipe begins to GLOW red after 7 minutes of use. Which would make me think clogged cat, but i think it's the fuel igniting in the downpipe just after that first little CAT. I'm sure that when the problem is fixed, this will go away as well, but i thought that was rather interesting.

Check the exhaust manifold for cracks. The manifold cracks quite often and SOMETIMES causes a misfire. Not quite sure why that happens but I've heard of it occuring at least twice.

You may need to check the primary wires to the coil to insure the ECM is pulsing it. The ECM itself provides the ignition pulse source.

If that's not the problem then other things to check are compression and fuel delivery.

!!!UPDATE!!!

I figured it out. After 3 days, $50 Coil Pack, $8 Spark Plugs, $35 Plug Wires, and a $85 Cam Positioning Sensor! None of that worked, but when I checked the harness that goes to the harness plugged into the Coil packs, I was checking the harness with my ohm meter. After figuring out nothing, lol, I put it together halfway (half the bolts on the intake and snug fitting the PCV hose and such. I started it just to see and it WAS ALIVE on all four. So When I unplugged it at the connector underneath the intake manifold and plugged it back in, it must of been oxidation or something. No, no cracks in the exaust manifold, i had to take the heat sheild off to better reach the Crank Positioning Sensor. Besides a crack in the exaust manifold would only lower the backpressure in the manifold, as long as the valves are working, that shouldn't affect the compression in the cylinders so i don't understand why you said that could cause misfire. Well, anything's possible. I unbolted the exaust after the second CAT to see what it would be like. just left it loose on the bolts. Sounds alright, but it felt like it had a little more punch. I bolted it back together. Was only to test and poke around with the exaust. I think i'm going to take out the muffler and get a boom tube or glass pack. Any suggestions. I want a little more growl, but not a loud rattling bumble bee like you find in the Acura Integras.