Correct Idle RPM for 4.8?

My 2001 extended cab with a 4.8 has recently began to idle at a lower rpm and idles erratically. Have replaced plugs and PCV valve and done the Sea Foam thing through the vacuum hose. Checked the fuel pressure regulator and the air filter, and no problems there.

Battery and alternator also checked out ok at Advance Auto. Even let the dealer ream me for 200 big ones to clean the injectors and throttle body, but the problem still exists! No codes are being produced.

Does anyone have any suggestions?

Respectfully frustrated.

How about a new fuel filter? Did you clean the IAC port of the throttle body?

Yes, did both of those.

there are a couple of GM TSBs regarding low idle concerns on those vehicles
Idle Instability, Low or Rough Idle with Electronic Throttle Control (Clean Throttle Body) #04-06-04-040 - (Jun 14, 2004)
andIncreased Accelerator Pedal Effort, Idle Instability (Clean Throttle Body and Adjust Blade) #02-06-04-054B - (Mar 17, 2003)

the first one is for electronically controlled throttle bodies and includes a calibration update.
the second one is for cable controlled throttle bodiesl

Thanks Merlin. The second would most likely apply to me since mine has a cable. Where can I get more information on the TSB?

actually if you do a search on this site for that TSB number it should show up, I think Merlin has posted it before

Thanks Jeremy. Tried a search with several different headings, but to no avail. Any ideas?

Found it: http://www.automotiveforums.com/vbulletin/showthread.php?t=210522&highlight=02-06-04-054B

Found it: http://www.automotiveforums.com/vbulletin/showthread.php?t=210522&highlight=02-06-04-054B


Thanks very much! I will pursue this with the local dealer.