Ferulic rest temp is around 110-115 the mash pH needs to be about 5.8. Do the ferulic thing, then wait until the mash pH drops to around 5.6 before you pull the decoction. If the mash hangs at 5.8, next time toss in some sauer malt after the ferulic rest. Now, remember, the main mash is going to be at acid rest temps and may continue to lower pH. Buy a yeast that will help with the clove flavor. Next time when you have more time, boil longer. A longer boil will reduce the protein gum and break down hardened starch stuck in the husk. I'm not sure about using Spec B with a decoction. If using it toss it in near the end of the decoction boil time. It might be too aggressive if boiled for the full time. Once you do enough decoctions, you'll be able to tell by the slickness of the mash in the decoction kettle during the boil, when everything is right on. Try not to scorch the decoction mash. Brew on, you'll do fine.