Help my all 3 of my provaris are shorting out my cartomizer!

I just dont get it, ive been vaping 3 years, one year on a provari. I've built my collection up to a total of 3, just got my newest on saturday. I bought 2.5 ohm cartos which measure at about that to begin with then after about 1/2 hour drop as low as 1.1, the cartos are fully saturated, not flooded and i've tested 3 different brand of cartos out all are doing the same on each mod! Like i said im no newb so i know its not my voltage either. Anyone ever had a provari short out your cartomizers? This just recently started about 2 weeks ago, i didnt think nothing of it but then i got my new mod saturday and the same damn thing! Help me im at a loss ive tried everything. I would really like to not have to send all 3 in and be stuck with my zmax