99 Chevy Silv DTC codes P0171, P0174--o2 sensors?

Truck is running erratic at idle, seems to surge. Have after market K&N air cleaner. SES light has been on (it's been cold). Cleaned MAF sensor, cleaned K&N air filter. The SES light still on, replaced the oxygen sensor on pass'r side front (before cat). SES off now, but the truck still sounds the same (runs erratic at idle). Think we should replace the other three oxygen sensors? Took it to AutoZone, they got DTC codes P0171 (bank one--too lean) and P0174 (bank two--too lean).

Since I've bought this thing it's run lean. SES light hasn't stayed on for no reason though. Think it's the other three oxygen sensors?
:screwy:

Welcome to AF. First this should have been posted in the Silverado truck forum, but anyway, vacuum leak, air entering the engine unmetered, low fuel pressure, all issues here so addt'l diagnostics are required, not sensors. Possible skewed maf, also the baro readings need to be confirmed as accurate, again needs a full scan here not AZ.

Thanks for the heads up on posting in the correct forum. Went back to try and edit the thread, but couldn't figure this out.

Anyway, we'll take the truck into the dealer tomorrow.

Thanks again,
SR