Furnace filter was replaced over 2 months ago, and has been in place for the full time and furnace has been quite busy during these 2 cold months.

When it kicks into gear : I hear a whir and what is probbaly the blower starting. Then maybe 30 seconds later the burners kick on and furnace tends to run for 3 maybe 4 minutes. It seems to be kicking on every 15 minutes. Outside temp has been from 18 to 25 degrees and I set thermostat at 70 during the day and at 65 at night.
I have 3 rooms with cathedral ceilings (top level of apartment complex).
I go to each of 3 vents in those rooms and one of them I can feel a very soft amount of air flowing out. The other barely anything blows - I can only feel some air 'dropping out of that vent, and the 3rd one I can not feel anything. Each of these are ceiling vents on the cathedral ceilings, and I do not have a ladder so my hand is probably 5 to 6 feet below the vent.

I am wanting to know if it sound likes normal 'efficency' for the furnace.. kicking on about every 15 minutes and running for 3 maybe 4, and if there is a way to test the blower 'power'? It seems weak to me. AND WHY THE AIR FILTER IS TOTALLY CLEAN AFTER MORE THEN 2 MONTHS FURNACE USE Thanks in advance for you help!

Furnace filter was replaced over 2 months ago, and has been in place for the full time and furnace has been quite busy during these 2 cold months.

When it kicks into gear : I hear a whir and what is probbaly the blower starting. Then maybe 30 seconds later the burners kick on and furnace tends to run for 3 maybe 4 minutes. It seems to be kicking on every 15 minutes. Outside temp has been from 18 to 25 degrees and I set thermostat at 70 during the day and at 65 at night.
I have 3 rooms with cathedral ceilings (top level of apartment complex).
I go to each of 3 vents in those rooms and one of them I can feel a very soft amount of air flowing out. The other barely anything blows - I can only feel some air 'dropping out of that vent, and the 3rd one I can not feel anything. Each of these are ceiling vents on the cathedral ceilings, and I do not have a ladder so my hand is probably 5 to 6 feet below the vent.

I am wanting to know if it sound likes normal 'efficency' for the furnace.. kicking on about every 15 minutes and running for 3 maybe 4, and if there is a way to test the blower 'power'? It seems weak to me. AND WHY THE AIR FILTER IS TOTALLY CLEAN AFTER MORE THEN 2 MONTHS FURNACE USE Thanks in advance for you help!

Yes it sounds normal. Thermostats set to gas operation usually have 6 cycles per hour but that is not a real accurate figure since it depende upon how cold it is in relationship to how tight(low heat loss) your home is. In other words it is not a perfect science.

If you home is comfortable there is no reason to test the blower since it is not the blower that really makes a difference but the amount of CFM (cubic feet per minute) that is moved not only by the blower but by the duct system and associated grill network.

You must have a VERY clean home since after two minths of use usually a normal home will show some dirt and in many cases it is time for the filter to be changed.