Have your dealer tech look up flushing the SCV pilot circuit, what you are describing sounds like there is very fine debris in the pilot circuit in the SCV stack causing the pilot valves to be sticky, performing the flush procedure will usually correct SCV's that do not respond correctly when making adjustments. 

I had a customer that had problems with this issue occasionally  so I made up a hose so he could flush it every couple days and it would work fine then.