What’s your fuel pressure? Around 52psi is normal idle I believe. Also the fuel strainer/pickup could be really dirty/clogged.

Fuel pressure is 52 @ idle.

I received my full speed density tune last night and it's a night and day difference! Hopefully that will be good for the long-term.

Thank you all for input!!

Why do you think your car ran OK for a few days after the swap, before the problem? Any ideas on the trigger?

I honestly have no idea. Other than the vacuum line to the BOV and removing the intercooler, literally no other air-carrying lines were even touched... A theory I have is maybe the MAF signal disparity was initially manageable but the addition of the 9lb pulley caused the imbalance to be too big? Maybe?

Even that I could argue you should see problems immediately following the install...

The other theory is that maybe the orientation of the coupling from the intercooler to the intake Y pipe is directing flow differently after removing and replacing the intercooler.

With the a2a setup the turbulence normally present at the stock stillen MAP sensor location goes away. If choosing to run the stillen manifold unmodified, then tapping in between the two throttle bodies is the way to go to get a clean manifold pressure reading with minimal turbulence.

Turbulence as reason make sense. What doesn't is how changing from W2A to A2A affects Turbulence. Air still flows past the same TBs in the same manner, albeit more flow overall. I'd be pretty concerned the characteristics changed so much inside the intake manifold to necessitate a change in MAP location.

I haven’t confirmed it myself but it’s what I recall he told me also. Perhaps someone that has both installed can do a few runs side by side and check the variation in the two different readings.

So you have two Mass Air Flow sensors that meter the air coming into the engine as it flows past them. There is also a Manifold Air Pressure sensor on the back driver's side of the intake manifold (stock or Stillen). With the a2w setup, that heat exchanger is in the way of air entering the intake manifold and getting to the engine. This can cause pressure fluctuations (turbulence) where the stock sensor position is. Moving the sensor to before that heat exchanger (n between the TBs) gives you a more accurate reading of manifold pressure.

With the a2a, that intercooler is not in the way and so the air flows through the TBs into a giant cavern (relatively no turbulence) before entering the engine.

Just my thought on the why, but I am not an expert.

Ahhh, forgot about that piece of crap Intercooler inside. I had erased that terrible thing from memory, lol. This is a fair point.