Small Engines (Lawn Mowers, etc.): engine looses power, grass clippings, john deer

Question
I have a scotts (john deer) 17.5 hp 2002 tractor mower
It starts good and runs good
when I engage the blades and the engine is worm it starts
loosing power, choking and almost kills. I disengage the blades and it regains power and runs fine.
I changed the oil, filter, gas filter, checked the air filter and it is clean, The gas is new & fresh.
The tractor is clean from any grass clippings and the bleades rotates fine.
any suggestion.

Answer
 Hello Karam:

 There are 3 possible causes for this Problem.  1- The Carb is out of Adjustment. 2- The Carb needs to be Cleaned and Overhauled. 3- Check the Compression. May need new Rings. Hope this Helps.

 Good Luck

 Respectfully

 John