So I have a 2004 G35X with ~104k miles, and I have Berk HFC's installed when my originals went bad, and lately another light came on and my car went into LIMP mode, wouldn't accelerate at all. Took it to the shop, he cleaned the MAF, worked for a day then did the same thing, so I had it replaced.

The car seems to run better, definitely more power and feels smoother but I'm getting horrible MPG now. I barely touch 18 MPG with wide open hwy driving, and before I was getting at least 22, and it has to be like 13 or 14 or even less driving around town. And I do not have a heavy foot.

Is there something I should have done, or reset maybe with the new MAF installed that would do this? Thanks for the help

 

Try resetting the ECU and performing the Idle Air Learning procedure. It's in the FSM