Banks 1 & 2 too lean 97 Explorer?? HELP

[hotwheels595]

Hi, i have a 97 Explorer V6 4.0 with the codes for lean banks 1 & 2.
Sitting at idle it has sort of a surge or hesitation but has no trouble accelerating.

I have only had this Explorer for about 2 months and no issues til now.
I did put seafoam in the gas tank when i first bought it and when it started
acting up i replaced the fuel filter which had a dark colored liquid coming out.

What could I do to problem solve this issue? I have read that this may be a vacuum
leak but i couldnt find one anywhere. Maybe a fuel issue?

 

[colintrax]

Probably a vacuum leak. They aren't always easy to find

 

[Dukes193]

I have had this issue for almost a year now and i havent been able to track it down. Im working on replacinv all the vacuum lines now.

 

[koda2000]

classic vacuum leak symptoms. check the PCV elbow, all vacuum lines or it could be intake manifold o-rings.

 

[hotwheels595]

I also hooked a scan tool up to read all the sensors while the vehicle
was running and found that all 3 of my heated oxygen sensors are showing
0. All the fuel trim readings were at -100 and those values did not change
when i made the idle go up. Now im really stumped but I have yet to
start digging deeper for vacuum leaks.