2011 Jeep Wrangler engine problems

I was driving my 2011 jeep wrangler about 5-8 MPH when I heard a pop type of noise. I then saw a flame under the hood on the passenger side. All of a sudden, my throttle locked up and my car wouldnt stop. I had both feet on the brakes, but my tires kept spinning. My electrical was locked up and I couldnt get the jeep out of drive and into park. My boyfriend ran over, jumped in the passenger side to try to get the jeep into park, as I couldnt get it to move.

I started to hear a knocking noise for 3-5 seconds on a cold start. It did not do this on any sequential starts for that day. Took it to the dealer, who changed oil filter and oil. Still made sound on receiving vehicle. Took in again and dealer replaced the lifters. Still made noise upon receipt. Took in for a third time, they are now saying it is a normal noise, even though it never made it before. Jeep specialists say that this is a normal noise as well.