I would love to have a great CAI like the ones that needswings provides, but with my retirement funds, I need to be a little creative. I came across and old post by onehundred80 that he did years ago using the air cover off a mercedes to improve airflow and filter size. He used I believe, the engine cover (air box) off a C320 Mercedes to modify his car. It was a great article and I pretty much followed it with one exception, and do have a few interesting numbers that show how effective this setup really is. I bought a used engine cover unit off ebay Part # A 112 090 11 01 and the front piece of this cover is A112 010 04 67. Then I bought a used 74mm throttle body A113 141 01 25 and the larger 74mm MAF A113 094 00 4 and still used the original 68mm MAF sensor just like onehundred80 did, then I made one change. Instead of using the mercedes air tubes that comes from the radiator support , back to the air box, I substituted HD 3" silicone radiator hose like they use for a kenworth. It handles the heat and contorts to fit the wierd shape holes that go through radiator support. Then I bought some thick funnels and cut them back to fit inside the hose to reestablish the 3" opening. The amazing thing to me is that the air filters on the Mercedes are right at 50% larger than are the crossfires and now if I do the math, the air tubes can handle almost 3 times the air of the original tubes.( included pics show the amazing difference) I did the whole project for about $150 and it looks like a clean installation, however: ( and not related to the engine cover or intake tubes) I have the dreaded idle surge that many owners have experienced after going to the 74mm throttle body and there are no air leaks. Oh well, I will keep working on that one,

original size on air tube through radiator support vs new 3"

3" hose contorting through oddball shaped openings

funnel inserted into hose to reestablish 3" opening
but the improvement in air flow which equates to oxygen has got to be huge as I live at 7500' of elevation, so hats off to onehundred80

 

Did you put the original MAF sensor into the 75mm MAF after taking out the 75mm sensor? You should use the original MAF sensor, it works just fine. The 75mm sensor causes problems like you have.
You could also have an air leak somewhere.

 

Yes I put the original 68mm maf sensor back on and there are no air leaks. I used a new o ring and both new rubber gaskets on the elbow, because like the rest of us, they had grown stiff over time

 

I heard some just drove the car and the surging sorted itself out. Mine purred nicely from the get go.

 

that is what I may have to do. It is just strange that it runs perfect part time and go nuts part time