In the Sept 2010 edition of "Car Craft" under "whats your problem" they document a problem I've noticed for several years. A cammed engine will throw a wideband oxygen sensor off since the overlap can pass unburned fuel into the exhaust. I started out with a LM1 the LM2 and now run a Autometer wideband O2 sensor in my car. At idle it shows 16:1 (top of the scale) but the instant I touch the accelerator it jumps to 14:1. What this means is that any EFI that goes closed loop at idle is going to be riching the mixture to overcome this seemingly lean condition. This is why all EFI systems come with a preloaded map to get you started. My question on the EZ EFI or any other "learning" system, whats it gonna do at idle.