If you are having Air-Fuel mixture problems... Clean your MAFs.
A couple of months ago my car started throwing a long series of fault codes, and lighting up the SES light.
- at full throttle, like passing another car on an uphill, the Beast would drop into a limp-home mode.
- when idling it would occasionally stall
- car misfired and ran rough
Well, my dealer charged me 2 hours labor to investigate, eventually finding a vacuum leak, and then reset the fault codes. Well, $200 bucks lighter, the car threw more fault codes on the way home.
They suspected I would need to replace both MAFs. Cost? $407 per MAF. Yikes!
And they weren't even sure that would fix it.
Well, I've been out of warranty for over 10K miles, so I didn't really want them spending more of my money to experiment with a fix. On their dime? Sure. On mine? Thanks, I'll do the experimentation.
So I bought a new MAF ($274 by mail) and swapped it in. Bingo! No more stalling, and runs much better at full tilt!
Well, I thought to myself, a while back somebody mentioned on the board that the K&N filter's oil had fouled their MAFs. I don't use K&Ns, but I'm sure after 60k miles there's some dirt in there. So I figures I'd clean out the old one and swap it back in.
All clean, replaced on the car... and... It Runs Great!
Dirt is your enemy.
Careful cleaning is your best weapon.
My solution might not fix your problem. Your mileage may vary. Blah, blah, blah.