Over the last couple of days, I've noticed that my engine of my 2003 TrailBlazer (Vortec 4200 I-6 engine) has been idling very low. Initially, when I start the vehicle up for the first time in a given day, it will settle junder under 1,000 RPMs (as expected).
However, later in the day, it'll idle around 600 RPMs. I never paid much attention to this until the other day I went from park to reverse / park to drive and when I pressed on the gas, it almost stalled on me.
I thought maybe I picked up some bad gasoline, but I don't think that'd explain the this very low idle.
What should the engine idle at after it's warmed up?
Also, does anyone know if this is a known issue and if any PCM updates have been released to fix this?
Thanks for any info.