i just recently replaced my MT with a used one but since ive done that every time i put it in third it kinda grinds then goes in like i missed a gear,it does it pretty bad when the car is cold but i found that if i shift it into third slowly it goes no problem.oh i also replaced my clutch.anyone have any idea what it could be?

could be a bad syncrode and also could be something messed up with the shifter. if you drive it hard and throw it into third it prolly would be the syncrode. try shifting into 3rd without using the clutch and see if it still grinds if it does then you might have an answer but only way to be sure is to tear into it (