02 explorer, more problems than its worth?

[024x4beast]

02 4x4 explorer with towing package- began first with the famous bucking, surging, pulsing, however you want to describe it. solved that issue by unplugging the transfer case motor to the 4x4. it wasd engaging eventhough the light on the dash wasnt illuminated.

then the engine light comes on. pull codes, turns out to be bank one running lean...why? hell if i can figure it out.
obd2 says its somewhere in either the EVAP or CAT. does this mean i have to shell out the $500+ on new CAT plus the $ of new EVAP canisters?

we have cleaned the MAF as it is fairly new, replaced some vac hoses, replaced the IAC and the o2 censors.

i am at a loss as to what this issue can be. Any Input?

 

[skeeter123]

How many miles? V6 or V8? What was the code #?

Has fuel filter ever been replaced? If not/don't know, check out:
http://www.explorerforum.com/forums/showthread.php?t=198626

Also, I'd check PCV valve and associated vacuum lines (if you haven't already).
http://www.explorerforum.com/forums/showthread.php?t=310053

Did you clear the codes after replacing some vacuum lines and O2 sensors, and then they came back?

 

[024x4beast]

Fuel filter has been replaced. The vehicle is a 2002 explorer 4.0L v6 engine NOT flex fuel: with 4x4 and towing pack. The vehicle currently has 136,200 miles on it. The code was p1131- lean bank 1 sensor 1. I am ordering a new sensor soon. PCV valve is fine. We cleared the codes, ran the car for about 10 mins and it was back.