93 240 Volvo wagon I've changed every sensor both fuel pumps new injectors the car only has 84000 miles and been maintained. The cars has a knocking sound when put into gear and it kind of goes away when driving but comes back when slowing down

 

Try to record it, post it on youtube or ? and add a link. Some sounds are very recognizable while others are just bewildering.
Automatic ? When you talk of a knocking sound, is it when you put it in gear but are still standing still (foot on brakes) ? If so you might want to check the condition of the motor mounts if you haven't already.