Hey guys this is my first writing on a forum. So basically I have a mk4 golf 2.0 and I replaced the engine for a new one with lower mileage and now the transmission slips. When I first drive it I have to wait until the rpms hit 4000 and that's when the transmission will switch to a higher gear. I can only drive it at 45mph or else the rpms go above 3000. All I did was just put a new engine and now it is slipping. Can anyone help me?