I know this is not an e30 but you guys are the most experienced at fitting s50's in strange places!

I am having a few teething problems with my engine though,
Firstly the idle is not smooth at all, i put it down to coil packs so i swapped a suspected faulty one and i got a slight improvement but still no where near smooth.
Next problem is the engine stalls if you let go of the throttle but it will idle if you gently release the throttle....
And then, it seems to be down on power, bottom end grunt is great but top end seems flat, almost as though the VANOS is not kicking in...
And fuel consumtion is HUUUUUUUGE

The only things i can think of that are not standard are,
I have not fitted this extra speed signal wire i have heard rumours about, apparently only M3 wiring looms had this wire so do i need to fit it? What does it do exactly?
Carbon canister sensor, i have a 328i one plugged in but it is not sensing anything, its just cable tied up.... What does this do exactly??