Sounds like what you bought is worn out. If it is not too late, I would take it back and tell them to fix it - for free. They should not have offered a vehicle with so many problems - unless they sold it cheap and told you something along those lines. "As is" is a common way of presenting a used vehicle, but the reputation of the seller is at stake when problems like this arise. Give them a chance to do the right thing. You may need to get in their face, but only as a last resort. What you have described may cost you thousands of dollars to repair.