Carpeting Issues- non molded carpeting

Heating the back side with the heat gun will work. Heat up a area and press into place and hold
till cool enough for it to take a set. This may take awhile due to having to work a small area at a
time.
I use a drapery steamer and work from the top side. Much easier and can form a larger area. This gets very hot so I use the rounded off end of a two by four to press/ hold carpet into the
contours of the floor pan till cool enough to be moulded into shape.