Trump says WAY too much. He’s all over the map and shoots from the lip.
I loved the way he slapped down the left instead of constantly turning the other cheek, but now he just comes across as unstable.
He's always come across "unstable" because he isn't grounded in conservatism. He is saying what he thinks conservatives want to hear, and if you are trying to become something you aren't it will eventually seem schizophrenic policy wise.
He huts himself with pointless rage tweets against people like Megyn Kelly who, like her or not, gives conservatives more airtime on her show (and with issues often framed in a conservative way) than almost any other major media host out there. For him to have little rants about her will eventually make people wonder about his temperament for the office of President. I think he hurt himself even more with the quasi truther stuff he pulled out of the hat the other week. Again, like GW Bush or not (and he was certainly not much of a conservative), most people on the right think he dealt with 9-11 pretty well. Trump seemed to be echoing a bunch of paulbot, InfoWars, Michael Moore truther garbage and I think that might account for his drop in the polls in Iowa.