Why does car shift hard into reverse and drive and some other gears?

I have a 1997 eagle talon with turbo engine. When I shift into drive or reverse, most of the time the car clanks/slams into gear pretty hard. Sometimes it even does it while shifting during driving. It is automatic transmission. The clanking is intermittent. Sometimes it won't do it all and it shifts nice and smooth, can't even feel it. Other times it can slam hard enough it makes the engine almost die. I have replaced all mounts on the engine and transmission. I have already replaced all engine and tranny mounts, which didn't do anything. I have checked the fluid and it is fine. Sometimes it slams hard enough the engine moves like three or four inches at least.