Cerve
Sorry to hear about the circumstances you are facing with the truck.
BBB is not going to help you too much in this case. As you now know, this falls within the domain of the state's AG office, consumer protection division.
As Foy mentioned, here in NC, the law requires dealers/sellers to be up front with warranty info (or as is) and description. Title (transfer) also requires owner (dealer) to certify if vehicle was subject to flood and/or damage exceeding 25% of the value of the vehicle.
Sadly, this is one of those deals you hate to hear about. Hindsight is always 20/20. Paying cash (cert check) for a vehicle sight unseen, across state lines is very worrisome and problematic. Dealing directly across state lines is problematic because individual states aren't strongly bound to intrastate commerce law and regulations; that's the federal domain.
Did the dealer have the vehicle listed on EBay Motors? If not that's a pretty good indicator there is likely a disconnect between the vehicle description and actual condition. Further using a brokerage service (such as EBay Motors) usually entails financial protection, albeit sometimes at and additional cost. But, worthwhile purchasing for peace of mind.
Again, sorry to hear about your frustration.
On a final note, you may not want to touch the truck (ie., change fluids) until the issue is completely resolved. If you perform any maintenance, it could be argued you have intent to keep the vehicle and release any and all claims to returning the vehicle and obtaining a refund. You might want to read the fine print in the buy/sell agreement. I would be surprised if there wasn't language stipulating all disputes would be resolved through arbitration. But, since the dealer hasn't mentioned that to you, such language may not be there.
Good luck and hoping for the best outcome for you.
