Taking twice as long to dry clothes

Having to cycle twice to dry clothes. Just started doing this.
Checked lint and no blockage in line.

I put a 12" thermometer where the dryer vents out of the house and i noticed that the temperature rises to (appx) 165 then immediately gos down to 130 and then rises back up and then gos back down. Takes maybe 1 minute to go up and then back down. Is that normal for a dryer?