i have a 1998 2ltr astra and i have a bangin sound comeing from the front every time i go ova bump, im pretty sure the suspension and springs are ok, Also when driveing on the motorway the steering don't feel right, sometimes the sterring goes light as hell and is very twitchy and then it goes back to normal. What could this be? i have had the tracking done but was ok

any help would be appreicated