Air to fuel ratio terrible

I've done a few tests on my 2010 Tacoma, im the 3rd or 4th owner of the the truck and i'm not entirely sure what has been done to it. Its running a ratio of about 9.8 while driving regularly and when you get on the gas it goes down to about 8.4. I get terrible gas mileage and I really want to fix it. Any ideas? I do have an exhaust on it but I imagine it would affect it that much when it's supposed to be about 14.7.

 

How are you getting the ratio? Lambda?
That’s so low you’d be triggering warning lights and possibly a flashing engine light.

 

Im pulling it from OBDII, I don't have any lights which is weird I guess.

 

You may be reading it wrong.
Go by fuel trim, lt ft % b1 and b2

 

What do the fuel trims say? (Short and long term - ST and LT)

 

I think Ill get a wideband and see it more acurately. Ill update this post if its still bad.

 

all at idle
Bank 1 lt: 4.69%
Bank 1 st: 0.78%
Bank 2 lt: 7.81%
Bank 2 st: 0.78%

 

It’s fine, running a little lean, clean maf and throttle plate. Check trims after.

10% up and Down is acceptable