Hello I have read many post when fixing my older f-150. I have recently purchased a used 2006 Lincoln mark lt with a 5.4 l engine 3 months ago. On March 1. I came to a quick stop in traffic. When I step on the accelerator I heard a clunk. Thinking that my u-joint might be going bad I thought oh well. Later in the evening when I was picking up my daughter I parked and left the truck running. I could then hear a random clunking noise. When I got home I checked the oil it was low but in range. I started it and put some Lucas oil in. I did not notice any difference, I crawled under the truck looking for something loose and found nothing. However I moved myself to the engine and put my hand on the oil pan and I could feel a clunk whenever I heard the noise. Today march 2 I went to start the truck it started but when the rpm slowed down it stalled. I tried starting again it would not start, tried again it did start however it stalled out again and now it does not start. I am afraid that this might be a busted rod. Any help would be grateful.