I have have the idle surge problem (up to 4000 rpm then down to 800 rpm on its' own) on my 99 SVT since 25000 miles. 3 trips to the dealer and I got a new Idle control valve, a new EGR valve, then it was not their problem any more because emmissions were not covered under the extended warranty. So I purchased 2 more ICVs at $70 a pop. Cleaned everyone of them and they were good for about a week. Last one went bad in 3 days... That told me for sure it was not the ICVs, It was the PCM.. I finally took it to another Ford dealer and they offered to check if my PCM had an updated code/software. Surprise surprise, had the old BAD CODE. New code was uploaded (only 42.50) and I have had no problems what so ever. So if those SOBs in your dealership say they know nothing about a code/software upgrade they are full of it...
