Rough Idle At Start Up!
 

I have a 2002 GMC Sierra 1500 4.8L, When I start it when its cold, it idles very rough hard to keep it running also running rich until it starts to warm up then all is good. no MIL.<!-- google_ad_section_end -->

I am currently having a similar problem with my 2000 2500 6.0. The "Extreme rough idle on cold start" post. I get a P0336 ( crank position sensor) code that clears up when the motor warms up and smooths out. It then runs fine the rest of the day no matter how many or how long my stops are. Earlier when not as bad, kind of your type scenario, I got a code for O2 sensor, bank 2 #2, replaced it, cleared that code then P0336 started. Now, after 10-15 minutes of warm up idling, it runs perfect. I'm reading about a driving procedure for having the ECM RE-LEARN the crank position sensor. I'll let you know

I am currently having a similar problem with my 2000 2500 6.0. The "Extreme rough idle on cold start" post. I get a P0336 ( crank position sensor) code that clears up when the motor warms up and smooths out. It then runs fine the rest of the day no matter how many or how long my stops are. Earlier when not as bad, kind of your type scenario, I got a code for O2 sensor, bank 2 #2, replaced it, cleared that code then P0336 started. Now, after 10-15 minutes of warm up idling, it runs perfect. I'm reading about a driving procedure for having the ECM RE-LEARN the crank position sensor. I'll let you know