I think the guys are right, FCA probably won't get involved.
Sounds like the dealer sold something he didn't have to sell (warranty), shame on him.
You believed the used car salesman when he sold you something you should have known did not apply (warranty on a modded car), shame on you.
I am not an atty but I play one on line! You still may have recourse. If your sales contract was for a car+warranty but you only received the car, he then failed to meet the terms, you can take action. You would not have purchased the car without the warranty so you can sue him for the full purchase price plus taxes, title, etc. You will need an atty. Maybe add punitive damages. May take couple years and maybe $10k or more, and you will need solid documentation. No guarantees on outcome, but no jury or judge likes used car salesmen.
You may get help from your state if you claim they defrauded you by selling a warranty then not delivering on it. Free and easy, start making calls.
Did you lease/finance with the dealer? Some states may allow you to stop payments, but only do so if you can confirm you are entitled to do so.
Be careful what you say, if you admit you knew the car was modded and FCA would not cover it, no one will be able to help you.