I just had my check engine light come on and I got a handheld diag device and it said p0171 system running too lean so I called Toyota of Seattle and told them I wanted to have them look at it since I bought a extended waranty and they did and determinded that it was the 02 sensor and they replaced it easy the waranty took care of all but the $50 deductable.

2000 4Runner Limited 3.4L 4WD: Brushguard, Yellow Optima Battery, Amsoil Air Filter, Denso Iridium IK16 Spark Plugs, Mobile Guardian,Eclipse 8435,Front Clear Corners and alot more....