-15 degrees, HELP GUYS

[mikejames68w]

2000 4Runner with 181k, V6 5 speed
-Six inch suspension lift
-315/75/16s
-Aftermarket front bumper
I live in NW PA and right now the average temperature is anywhere from -15 to 5 degrees. Over the weekend my exhaust popped off at the cat converter while I was wheeling, as expected my Check Engine light popped on due to the O2 sensors.. before I was able to get it fixed the truck began to stall out while on the interstate like it wasn't getting enough air, so I popped off the freshly cleaned and oiled K&N filter, rig ran fine from there on out. Two days ago I took it to my yota dealership/maintenance shop and had it all checked over just to be sure.. they said I was running three codes: Bank 1 & 2 lean fuel and 02 sensor.. mechanic cleaned my MAS air sensor in the intake, told me to get my exhaust welded back on and it would all clear up.
Tonight I had my exhaust welded back on and as soon as I did all of the lights were gone, good as new. The temp is currently around -20 and after driving it a grand total of about 25 miles the check engine light is back on.. is it probable that because of the extreme cold the rig is throwing the light back on or should I take it back to the shop to have it gone over again?

 

[02SE]

I would look for damaged wiring for the AFR/O2 sensors. Force that could pull the exhaust system apart, can certainly damage the relatively weak wires, which would then trigger a CEL.

 

[thebrandon]

Freshly cleaned MAF and welded exhaust fixed it the first time? I would look at the MAF again. Perhaps that K&N is slinging more oil on it than you think. Try a simple cleaning of the MAF to see if it helps to smooth things out. Sometimes those fancy K&N filters cause more trouble than anything else, especially if you over oil them.

 

[Doc2012]

I'm saying the K&N is freezing, blocking the the air from getting through the filter the right way.

 

[thor999]

I was told our MAS does NOT like oiled air filters, replace with stock and clean the MAS again, along with the TBI. I quit throwing codes when I did this.

 

[Skinfaxi]

First step is to see which codes came back.

 

[ben550]

I'm saying the K&N is freezing, blocking the the air from getting through the filter the right way.

Sounds about right.