The computer will cut fuel when it thinks its not getting enough air. Manually disabling the individual components in the intake is not going to cure the problem. A P1404 code will cause the car to try to run a system function test repeatedly until the fault is no longer present. Thats probably the fluctuation you're experiencing. At this point I would fix the EGR. The EGR valve itself also has a position sensor. Its not a simple ON/OFF system.

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CENSORED due to not family friendly words

Yep - I just confirmed what you just posted. I removed the zip tie from the intake butterfly and added 2 to the resonance flaps and it still runs the same. Mostly this was my curiosity to determine whether the computer was defueling or if the flaps weren't shifting. So, I guess this weekend it's time to do the EGR mod and major cleaning and see if that helps...

It really sucks driving this thing in Metro Atlanta traffic with no power!

BTW - part of the problem is that I don't have ready access to a scan tool, so I haven't actually seen the P1404