Question on check engine light..

I have a 1996 Toyota Tacoma 3.4V6 4x4 with 278,000 miles. Ever since 200,000 miles i have been running mid-grade in the engine due to if I run regular unleaded the check engine light comes on but as soon as mid-grade is put back in it cuts off. I read the codes and it always reads O2 sensor 1 & 2. Recently my gas mileage has taken a downfall and wondering if the O2 sensors is the cause? I run a K&N cold air intake but i clean my MAF every time i clean and re-oil the filter. Any suggestions?

 

when's the last time you changed your O2?

it directly relates to how much fuel mixture the ecu puts in so very well could be.

 

I think it was around 158,000 when it was last changed. Timing and water pump etc. was done at 211,000 I don't think O2 sensors where replaced then

 

you probably fouled the maf sensor try cleaning it first super easy

try that for a tank if it doesnt work then you can change the maf and o2 sensor

 

Ill give it a try. Truck is still a daily drive till i buy another Tacoma in a few months then this truck will get a major overhaul.

 

I wonder what made you come to that conclusion?