2005 Kia Sedona front end noise

I've been having nioses coming from the front suspension for the last 10000k miles, slowly getting worst. Sometimes it sounds like a bouncing basketball. Sometimes it sounds like the struct was stuck solid as I hit a bump casing a loud metal to metal thomp sound. On certain roads the van feels like a low rider, very stuff response with very little give. All other bumps and dips causes thumping sounds. Anybody have an idea because the dealer doesn't after at least 4 visits.