RPMs were dropping at idle, and esp in reverse from 1000 to just under...CEL was on...dealer said to give it a tune up...we replaced the spark plugs, ignition coils, and turbo (something)...the CEL went off and the car has been running much, much better. however, after accelerating, SOMETIMES the RPMs still drop-almost to a complete stall and the winter gear arrow pops up on the dash. This lasts just a second. Ideas??

 

Try cleaning the throttle body that should fix it.

 

Thanks! That seems to be the general consensus too.