HELP: OBD Code: P0171 running out of ideas

[LatinDragonXJC]

OBD II P0171 Fuel System Too Lean (Bank 1)

Lean Mixture = Too much air, not enough fuel

It seems fairly common on this board through my searches, but it also very common on boosted rides. Mine is not.

I did have a INJEN SRI in there, I took it out today (reinstalled the OEM). Cleared the codes, started driving, and of course it came back.

According to my Googling, a common misdiagnosis is "change your 02 sensors". I got my 02 sensors changed when I bought the car by the Toyota dealership, about 5 years ago.

Here's a summary what I've done:
*Cleaned the MAF with MAF cleaner
*Reinstalled OEM Intake

Any other ideas? My next step is to get some fuel injector cleaner (which I usually avoid).

[LatinDragonXJC]

Thanks for all your input SG I'll just write the results for any future searches.

It was my Brake booster, that was causing a vacuum leak.

The first shop I went to, told me it would be $650 ($325 for BB + $325 for Labor) to swap it out, . For 8 bolts?!

Next shop said it would be $180 bucks if I find the part myself and he couldn't do it that day (I needed it same day for vehicle inspection)

I finally used a hook up at a wholesale parts store (Buy Wise) and got the Brake Booster for $228.

Went to my father's mechanic, he said he'll install it for a $100 and get it done before the end of the day. No more hissing, no CEL yet.

Now it's time to sell my Lara, part-out thread coming soon.

Pictures coming soon:
Injen SRI
VVME HID kit for headlights and fog lights
(possibly) Greddy Evo II