I don’t know where all his support is suppose to be coming from, I see very little of it on FR.
I noticed in the Fox poll that Huck was at 5% up from 2% previously. That could mean they are polling more evangelicals in order to get the outcome they want.
If you took that extra 3% away from Carson he would be at 21%. If you gave it to Trump he would be at 27% which would be in line with other polls.
I agree with the people who say Carson is a parking lot for Trump voters who aren’t quite ready to be all in on Trump.