Hi. I just purchased my first Monte Carlo, a 2006 LT with the 3900 V6. The car has 65,000 miles on her and was up kept well and runs good. I however have noticed an issue with the headlights, guage cluster and interior lights having a slight flicker at idle. I replaced the alternator but that did not change anything. The battery was put in back in March of this year. The RPMs were not sitting steady either while this happened, going back and fourth between about 600-700 or so, you could hear the power go up and down. I ran a bottle of seafoam through the gas and now it is idling smoother but still feels a bit rougher then it should, sitting right around 700. The lights still flicker a bit. Something electrical? Or possibly maybe the throttle body needs cleaned out? Or maybe there is carb build up in the EGR system? No SES light at this time and under power runs well with no flickering. Thanks!