Did the search and had no luck, in the last month I have noticed several times when it is cold outside my idle is very low upon start up. The truck runs and idles very smooth, just do not know why the tack would show less than 500 rpm at idle.

Any ideas, I have 88k on the clock.

 

Could be the beginning of the tach issue that 2006's seem to have. Mine either reads 0 or is pegged backwards.

 

What issue is that?? Parked in the garage overnight this am, 50 deg and had the same thing tack showed about 200 rpms. On the way to work at 50 mph the tack was reading 1000 rmp. Truck runs and sounds fine though

 

Sure does aound like the 2006 tach issue. Search here and you will find several posts about them. Mine shows 500 at idle now but all other driving is normal readings.