He's not saying its idling at 200-250 rpms. What hes saying is that coming out of gear going down to idle, the tach will dip passed 600, tap 200-250 rpms, then come back up to 600 rpms. As most have said, 90% of the time its a MAF or TB in need of some TLC. I'm pretty sure that a compression loss (across the motor, not just one cylinder) would result in a similar problem, however, you'd notice a loss of compression in the general driving of the car alot faster than the idle dipping.

 

i was looking at it on the way home and according to my gauge i was at 1900 RPM and my digital said i was at 2000. POS gauge!

-sean