It's hard to clean the valve-train with an idle flush, from what I've gathered.
Best to drive with good oil for a couple years, make sure the PCV system is fine and other maintenance is kept up. Then, if at that time you desire get something that is a non-solvent flush. I like Amsoil's, Lubegard's, and some other products. I've used Lubro Moly's Pro Line Engine Flush once, but after 2 uses of Amsoil's product. The Amsoil removed some grainy carbon deposits each time, however it's hard to know where it came from and it's not scientific. I didn't get extreme removal of anything with the LM, though that was well after I had gotten the vehicle into good maintenance practice for almost 2 years.
Caution for now is the best approach, IMO. If you use MMO, do that in the winter not the summer. Especially if you are doing any hauling still. The same goes for 'kreen treatment' cycles.