hey everyone i have a 2001 acura cls with code p0171.. i really don't know whats going on. A couple people told me o2 sensors but i changed downstream and upstream two times in a month... i also did a tune up and changed main relay. Car shakes after being drove for more then 30min. when i go to start it up it takes me a while to get it going

 

I have the same exact failure. I was thinking it could possibly be my fuel pump but it is weird that it happens only after a short time of running the car sometimes it varies.

 

that was what a few people told me too.. but like u said after driving a while it does it on and off. sometimes it has a crazy smell and my engine shakes when sitting at the light... here are somethings i am going change. fuel pressure regulator, cat, fuel pump