03 Silverado idle issues

[Thorn]

Hi there, I have an odd issue with my 03 silverado. It will start and idle fine, you can rev it up just fine. When you let off the throttle it will idle down if in nuetral to ~200 rpm then pick back up. When you let off the throttle and you have it in gear it cuts off, almost like you turned the ignition off. The engine is not missing or misfiring, and sounds good when you rev it up. The truck has a 327 vortec v8 (4.8 liter), auto trans, 2wd. Any ideas?

[TerryAuto]

Sounds like maybe just carbon in the throttle body bore and plate.
Saw a description of how to clean it at these guys main site. Just do a search of this site using"silverado carbon", or "silverado throttle idle", or something like that...
Clean Carbon From Throttle

[Terry]

2001 CHEVY 2500HD 6.0L Vortec.
SERVICE ENGINE SOON P0140
Repair work done prior O2 SENSORS LAST YEAR.
DOWNSTREAM OXYGEN SENSOR ( LEFT CYLINDER BANK ) CIRCUIT INSUFFICIENT ACTIVITY WERE IS IT LOCATED IS IT A SIMPLE FIX ?

[TerryAuto]

2001 CHEVY 2500HD 6.0L Vortec.
SERVICE ENGINE SOON P0140
Repair work done prior O2 SENSORS LAST YEAR.
DOWNSTREAM OXYGEN SENSOR ( LEFT CYLINDER BANK ) CIRCUIT INSUFFICIENT ACTIVITY WERE IS IT LOCATED IS IT A SIMPLE FIX ?

This code refers to the oxygen sensor after the cataytic converter. you wuld need a 7/8 wrench, or better yet an O2 sensor socket. These can be purchased at any parts store.

[butchkaz]

If your Silverado also has misfires on the odd number cylinders, you may have a bad catalytic converter. You cannot replace just the one, you must replace the whole "Y" pipe assembly which includes both side pipes and converters.