Help code p0171

[Joe jones]

My Explorer starts and drives fine until temp then dies the o2 sensor by the cat (upstream) is greasy and old looking and my egr looks like it's missing a hose please help....!

 

[GTMountain]

Lean on cyl one. Do a home smoke test and see if you're leaking air. Previous owner might have done an egr delete or you hose rusted off. Codes ?