At idle/cruise we mainly use lambda AFR of 1.0?

Effect of AFR on Economy. I got confused so please correct me if I'm wrong..

So at idle/cruise, a stoichiometric AFR target of 1.0 is a better choice?

And the leaner the AFR, the less power it makes then we need to increase the throttle opening which leads to more fuel consumption?

Stoichiometric AFR and Lambda are two different things. AFR is your mixture of air and fuel, which is 14.7 parts air to 1 part fuel, 14.7:1 or just an AFR of 14.7. If your talking in lambda values then the stoichiometric value is 1.

With that all said in relation to your question, are you sure your timing is set up correctly for idle and cruise? You will need a certain amount of fuel or else your just pumping fresh air so there is only so lean you can run the engine.