At the end of the cycle about the last 2 minutes my furnace blows cold air. How do I stop this?

Your furnace flame shuts off when the set temperature is reached. The blower conitinues to run for several more minutes to get all of the heat you paid for. I set my thermostat to run the blower 24 hours per day. Sounds wasteful but it is not. The blower requires quite a bit of electrical energy to start from a dead stop. Letting the blower run all of the time cost only marginally more. In addition the blower motor will last longer and the house temperature will be more even.
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Depending on the furnace you have, you can change the length of time that the blower blows. Some have an adjustable fan switch on the fire wall of the furnace,(this is just above the burners, again depending on what kind of furnace you have, this would be an upflow furnace) On this fan switch you can set the temp you want the fan to go off.
Newer furnaces with circuit boards have a time setting that you move a wire to a different post to get a shorter time for the fan to run. On the circuit board you will see three or four post that are marked something like; 180 seconds, 120 seconds 90 second. Move the spade clipped wire to one of the smaller numbers.
And of course there are others,. so give me a hint at to what you have,