A new "my lt1 runs like poo" thread :p

[bottledbird68]

Ok, wound up driving the z an hour home in the pouring rain after work Thursday night. Car was running mint but now not so much. It started popping, sputtering, and backfiring randomly on the highway on my way home and now, even after the rain has stopped, is still doing it.
I did a quick look around at all the wires and everything looks ok but it feels like it's down a cylinder or two.
At first anything under 2500 rpm was horrible and almost undriveable. Now, it's cleared up a little, but still not so great under 2000 and downright horrible under 1500. It does however idle great and starts right up fine. It will pull all the way through to redline without too much drama but you can definitely tell it's just not all there. My other half said it best when she drove it, "the gas pedal feels like a spongy brake would react"
Not throwing any codes so could it still be the opti? It really feels just like a plug wire is shorting out but they look fine everywhere. Any ideas before I tear the front of the motor off, AGAIN!!!