Hey guys, I bought my car with the aFe intake already installed and didn't get the OEM intake. Personally I probably would never have changed the intake from the stock one, however... since the AFe was already installed and the OEM parts were long gone... I really didn't have a choice.
With that being said I'd lived with the surging for nearly 2 years and mostly got used to it, but it always bugged me in the back of my mind. After reading this thread I was determined to give it a shot.
The only thing I really did much different from the original poster is to make mine out of Delrin which is a pretty strong plastic... probably much stronger than what the aFe intake is made out of (guessing ABS). The benefit was that its easy to work with (for me) compared to aluminum. I just ordered a 6x6x.5 inch black sheet from a plastics supply company on-line.
Anyway, spacer works exactly as described and my car is <much> better behaved now, I can't thank the OP enough for posting this fix.