I have kenmore model 110.63952101 it runs for a while then shuts down like an over heat poblem, but it runs longer if I am drying jeans could it be motor or heating elment problem?

It could be too much lint in the dryer. Clean out the dryer and exhaust vent of all lint and try to blow the dryer motor out with compressed air. Many times the lint builds up especially around and in the dryer motor causing it to over heat.