It seems strange that the wrong head gasket would make it rich though? I suppose if it's not burning correctly, the mixture out the tailpipe will be unburned and rich with fuel.
You can always also adjust the target lambda the ecu is aiming for. Stock for emissions will be lambda:1 but if you run slightly richer than that, say down at 13:1 AFR it always smooths out a slightly lumpy idle.
I suspect the idle is to do with your exhaust cam, more duration does that... Try richening up the target mixture and it will stock the fuel trims pulling it lean too!
JP
You can always also adjust the target lambda the ecu is aiming for. Stock for emissions will be lambda:1 but if you run slightly richer than that, say down at 13:1 AFR it always smooths out a slightly lumpy idle.
I suspect the idle is to do with your exhaust cam, more duration does that... Try richening up the target mixture and it will stock the fuel trims pulling it lean too!
JP
JP