My coleman 7900 furnace blower cycles on and off while burner continues to operate

I would look at fan limit switch. They are normally located in electrical cotrol compartment. If your are lucky you will have one thats adjustable. It would helpful if I knew is your home a mobile or modular home as they usually use a button type limit on fan and hi limit. It sounds to me like you may be having problems with fan limit which controls temp. that fan comes on . Often what happens is that switch scenses temp to turn on and then draws cold enough air on return air to shut back down until temp.rises again.If this occurs when unit first comes on or continues after burner shuts off you can get a limit switch with a higher temperature rating or one that has adjustable temperature range. Hope this helps you.Thanks.