how I turned off lean codes p0171 and p0174 for $5
 

short answer, cleaned air filter and a $5 can of AFS cleaner !

stealership wanted to start trouble shooting at $120/hr. "cus those error codes could be a number of things.....blah blah"

so I cleaned the MAF sensor and cleaned and dried the air filter.
re-assembled and voila !

nice smooth idle and no check engine light now for 1000kms

My 2004 AL is running solid again