How many watts are you using(assuming it's VV/VW)? If it's a mech mod, you may only get 10-20 good vapes at max battery, then it'll slowly decline until your battery is pushing nothing out. Also, do you mean 8 wraps per piece of kanthal(16 wraps total)? or 8 wraps total (4 per piece)? 3.5 ohms seems awfully high for a parallel, especially a dual (sided?) parallel. Depending on the wraps I use, I usually get about .4-.7 ohms on my dual parallel builds (using 26 or 24g kanthal)