I have a five year old hotpoint gas dryer. My problem is when I start the dryer, it heats great. After about 4-5 minutes it stops heating. I ran the dryer empty with the vent disconnected... heated fine. Ran it with the vent hooked up, dryer empty... heated fine. Ran the dryer with a load of clothes, back to the original problem. I have thoroughly cleaned the inside of the dryer, vent, burner tube, air inlet louvres, and blower fan. I am baffled as to why it will heat with no clothes but won't heat properly with clothes. I had great air flow with empty dryer, vent disconnected but pulsating air flow with vent disconnected with clothes in. I imagine the clothes as they tumble temporarily block the lint trap opening but this must be normal operation. Can someone point me in the right direction before I point this appliance out the back door?

Have you checked the drum seal?