I was just down in La, Baton Rouge, last week. Too humid for me! I don't think your problem is caused by fuel or air filter. A good place to start is to follow Drew's advice on the previous post. Do a compression check, then do a dynamic compression check along with a snap throttle test and compare results. Look in the General Camaro Tech section. I posted to spongebob last week under "low cranking pressure" for details on how to do the test and why it works. If you have a problem with an individual cylinder breathing ability the dynamic test WILL point it out. Remember the direct ignition system fires two cylinder at the same time, so if you are sure about your condition of your wires the coil if weak would be misfiring two cylinders usually. It fires on the power and exhaust stroke, it was simplier to make the system this way and it doesn't take much energy to fire a cylinder on it's exhaust stroke compared to compression or power stroke. Anyway I think a bad coil or coils isn't your problem. Did you replace the ignition module that they plug into? That has been a very troublesome unit for GM as has the ECM or computer. I've had both go bad in the past. I've also had crank sensors go bad as Drew suggests. If the monopole (crank sensor) is losing it's magnetism or is damaged placing the tip too far away from the triggering mechanism it can cause these kinds of misfires. The sensor usually isn't too difficult to replace or expensive from my experience. It's unfortunate that you've had the problem on two different vehicles now.