roper dryer overheats?

this one has me baffled, my dryer would not heat so i took it apart, when the element was out it would work when screwed back in place it would not,so i tested everything and the only thing i could think off was the high and low thermostats,i changed them and it worked for a day or so, then on one load it practically melted the clothes then shut off and the timing dial barely moved, now it won't start so i checked the fuse in the back and that is bad so today i am going to change thatbut what if it works again and burns the clothes and shuts off again, any ideas.i am a better than average handyman but this one has me going in cycles i mean circles,help.