Omega’s swimming!

Hello, I have a big problem with the Omega again. The car “swimms” suddenly on normal, straight track. It feels like I’m driving over a pothole (but it happens on perfect asphalt, I’ve taken care of it). I lose control for a short time, the car pulls off briefly to the right and back again. Aren’t the wheels screwed? Do the tires eggs? Or is it on the rear wheel drive? Felix 🙂