Well guys im out of ideas. My lt1 is still sputtering and backfiring at wide open throttle. It drives good on moderate accelerdation but wide iopen throttle it has serious break up. I replaced the opti thinking it would fix the problem. It didnt i sent the opti back and replaced it again thinking the opti i bought was bad two in one week. I changed coil, wires, plugs, icm, and knock sensor because i got a code 43. It cleared the 43 after replacing knock sensor. But that was the only code i got strange though. Im running open headers no cats. Cold air intake, electric water pump bbk under drive pulley 255 walbro pump. Shouldnt i get a code for o2 sesnsors??? simple fact becasuse im running no cats and open headers. I use to get a code but now im not. Im no tech i just turn wrenches and past that i get lost.. I double checked wires made sure their not touching primary and arching also the wires are not crossed.

 

what is your spark plugs gapped at? I would gap them .035-40
Also might check your fuel lines motor to tank and make sure the big plastic fuel line isnt pinched or kinked anywhere.

 

at WOT your O2's could be making your car rich.the O2's could be getting a cold drift which would dump more fuel, then you need in the engine causing it to buck and back fire.....