This does not sound like a VSS issue to me, this sounds more like a TPS issue, which is a known spratic problem with these trucks.
You will be driving along and the engine will return to idle for no reason and then come back.

 

Ok, without checking RAVE, where is the TPS and how common is the known issue? This is the first time I've heard this. Help me Obe 1 Knobe, you're my only hope.