Wow, you must be really coughing to feel like throwing up man! Heat and water are big factors, as Caligula says. The other thing is that we often like to take gargantuan hits (especially those who used to combust using water tools!) when vaping. Large hits of dry vapor can be especially good at making you cough a lot compared to combustion smoke. Vaporizing seems to be a bit harsher dry for me than smoking.
Caligula is spot on, use water for higher heats when vaping. I find that if I vape dry at the heat range you are doing through your ascent, I will cough a lot using a shorter vapor path (ie: the Nano dry stem I have) vs a longer dry pipe (Gspot Steamroller) with roughly the same sized hits on each. I am given to understand that the Ascent stem is shorter than the Nano stem, so might be harsher still at your set heat than my Nano stem even. I also find I need to not take in quite so big hits when doing dry vaping at this temperature as what I would with water.
There are loads more factors that could contribute to this scenario you have found yourself in, Caligula did a good job of outlining plenty of others.
Don't worry though, it's all about finding your groove with the vape, practice makes perfect