Issues with RF build

I have Marauder Level 78, I haven't played since patch 1.2.
Previously I used Oro's RF build, I had no problems.
Now I moved to Cocotheone RF build - one of top RF builds in forum.
So I reallocated passives.

My stats ar now:
6.3k HP
933 regen
87% fire resist

1. Issue
- when I change zones, my fire resist drops to 82%, my RF does more dmg to me than my regen can keep up, then my HP drops to 30% and resist increases back to 87%, so now I regen normally.

2. Issue
- so when my resist are back to 87%, it looks like it's fine now, but it's not. Whenever I take any action (use flask, any ability, switch any gem, use totems, mob hits me...) my HP resets back to around 30% and starts to regen back. Also if I use flasks it does not only reset my hp, but also drop my regen somehow (any life flask), so it resets to 30% and degen my life for few secs, then again starts to regen slowly.

I can't do any maps normally now, because any action drops me below 30% and random degens appears. Mobs doesn't hit me hard, but anyway it's very difficult to focus on those 30% like it was my MAX HP..

I have no idea why I have this kind of problems, I have tried to remove gems, left only RF, Purity of Fire and Vitality, but same thing happens. My gear also doesn't have any buffs/debuffs that affect my HP regen, only basic regens. Also passive tree doesn't seem to have anything wrong there..

Is this some kind of bug or what? I am really confused, never happened to me before. It was perfect on 1.2

Link you gear and tree and maybe we can see something you're missing. Your extra resists from you shield would kick in when you're at 35% life, so that might be why you see that as the point where it fixes itself. But I don't know offhand why you'd lose life before that. I might be able to tell if I saw your gear/passives.

Also, I wanna note, that in hideout there are no flask glitches, RF works smoothly. These issues appear only in combat maps.

Tree: http://www.pathofexile.com/passive-skill-tree/AAAAAgEAAdwB5wSzBS0GDgn2DF8NzRJpFCAUTRZvGJEZLhpVGmwcpxzOJKon1SftKPorUDboNuk64TwFPC09Dz38QYdDyEWdR35M_1BHU1JTpVW1Vw1YY1ugXz9gS2EhZKNo8nTtdqx8DoIHgseE2YTvhymMz5itmuCdrp7Nn9-iAKcIpzCnVa2Nr2y3PriTvJ-9NsBmwQTEWMT2xq7G2M9-0iHUfNi92WHZfOLq42rr7u8O73zwH_JB8kX2SPno_Ev-Cv5U

Items:

Looking at your passives and gear, it looks like you only have 135% fire resistance, which is 75% in Merciless (99% from gear and 36% from purity of fire). The only time you reach your maximum of 87% is when you hit low life and your shield gives you more fire resistance (and your amulet gives you another 1% regen). Add 12% more to your gear and I think you won't see a problem anymore. It works fine in your hideout because it's a normal area so you don't have the -60% resistance penalty.