Don't want to go back to mechanic

[Yisroel K]

Hello, I bought a 1999 4runner about 2 years ago. The truck ran great until about 6 months ago I went to mechanic to fix breaks and rotors. The mechanic ended up switching out both axles, 4 breaks and rotors, and he told me he welded up my muffler. about 4 months ago the muffler sounded really bad but the truck was running fine so I left it. a month ago my check engine light came on with p0170. I went under the car to see it any hole on muffler (i though maybe check engine light from muffler) I saw the rear o2 sensor unplugged and hanging. I went to the store-bought a new gasket and put it back. the truck sounds great but engine light is still on. the truck is running really rich (100 miles per tank) I checked for vacuum leaks and cleaned the MAF but doesn't seem to help.

Please help.

 

[KyleB4279]

The P0170 code could be caused by a few things other than the O2 sensor. It could be caused by a clogged fuel filter, weak fuel pump, or faulty pressure regulator.
Even though you have cleaned your MAF sensor, it could be bad. See if you can have the codes cleared from the ECM - any auto parts store should be able to do that for free. Drive for a bit and see if you get any new codes to come up. There are some codes that are specific to the MAF sensor that may come up.