454cid
Sooper Pooper
It acted the same spitting sputtering and stalling
That must mean something else is throwing off the info coming from the MAF, then.
What does the voltage look like on the front O2 sensors? What's the MAP sensor doing? I've never had to deal with the MAP sensor, so I'm not sure how it would affect the engine running. O2s can casue misfireing, although your fuel trims don't look horrible.