Death Wobble

this past Friday I purchased a 203 jeep wrangled sahara unlimited 29,000 milesWhile out running errands on Saturday the car began to wobble uncontrollably causing it difficult to even stopI googled the issue to learn its called the "Death Wobble" and could actually be several different issues I contacted the dealer and I want to return the vehicleIt appears that the car was lifted after factor and had other modifications to add additional featuresI believe the dealer wants to try and repair the car but I'm concerned (as if read on line) that the problem may still persist because it is hard to pin point it as one single issue I'm more concerned that since their was modifications does that void the factory warranteePlease advise I'm deeply concerned and upset because my main reason for purchasing the jeep was for its history for safety