Toyota Corolla Verso 2008 / 1.8 Petrol Manual Gear / 1ZZ-FE / European version of Toyota Matrix

Hi Scotty, i have replaced the Clutch set at the Toyota Dealership like 1 month ago, The Clutch Set is OEM Aisin, i think KT-135
i have traveled like 800 miles, and everything was working perfect, but suddenly the car began to shake when i am taking of, when i release the clutch pedal like less than an inch the car is shaking very strong, as well when i drive for example on third gear, when i want to slow down, i downshift to 2nd gear, and when i begin to release the clutch, the car, the pedals first shakes than you feel that the rpm rises. I noticed that it shakes worst when there is a load like hill or this kind, Otherwise the clutch pedal is smooth and it is not hard but quite normal. This car as i know have hydraulic engine mounts, i have checked, there is no hydraulic fluid leaking, and the hydraulic fluid shows Full-hot, when the car is worm, and Full-Cold, when the car is Cold.
I have noticed that when the car is cold the vibrations feels much lighter, when i drive the car specially in traffic, it get worst. 
There is no Check-Engine light, or any Error codes on the Diagnostic Tool.

I drove the car back to the Toyota Dealership, they lifted the car, checked the gearbox, if there is any oil leakage, they checked the engine, and gearbox mounts, they said there is no fault codes, and said that all seams good, and they don't know why the car vibrates, and shakes this way after the clutch replacement, they advised that maybe because the clutch is new, that i do not believe it :/ . 

I will be thankful if you have any idea what to check. 

Thank you so much in advance !