APM 2.6 without GPS module and aircraft arming but is'nt stable in stablize mode , why?

I am unable to stabilize my quadcopter with the use of APM 2.6 , Unable to takeoff from the ground because its very unstable and likely will crash before even hovering of the ground, knowing that i can see its trying to stabilize itself when i tilt it by hand so the IMU feedback are working but not fast enough to stabilize my craft , frankly i saw many vedios on the internet for those who make quads and stabilize it easily with Apm 2.6 this is not the case for me and i was unfortunate .
please any one can guide me throught the process and i can try anything he/ she proposes and supply them with tlog files and vedios for any procedure he/she thinks its helpful for my quad to get up in the air with stability please help and i will never forget it…?
I am using emax motors with simonk escs and self locking props best in the market and i am using APM 2.6 and took off the GPS module because i am intrested in flying the drone indoors with stabilize mode and i am intrested in its stability more than anything else…
vedios , images , logs and everything would be supplied upon any test suggested by any of the community members.