Good run yesterday. However I would have thought that dehydration would increase your heart rate if anything. I haven't done physiology for a while but if your dehydrated then you have less circulating intravascular volume and your body compensates for this to maintain cardiac output by increasing heart rate.
I'm not sure whether ur looking for input, but I'd love to see u run well and achieve your goals so I'm going to add my 2-penneth.
Have you considered taking a good rest period before your next assault on a race? Perhaps you cant put in your full effort as there is a level of residual fatigue constantly in the mix.
I remember when you ran parliament hill cross country and had the shits afterwards. You had 3-4 days off and smashed every pb going when u got back into it.
Why not take a risk and take 2 weeks now then build up for Berlin? You cant question your commitment to training, maybe the only thing missing is recovery? Just a thought. Hope it works out if u try it.
Cheers guys, I am looking for input so that's really useful.