Hello, I have a 2004 Yukon Denali with 260k miles on it. The SUV is Pretty well kept and taken care of (I can provide car fax if needed) but recently after an oil change I decided to take the car on the road. Driving there was fine, (I have pipes so I cant really hear engine noise as vivdly) no problems as I knew of. However starting the car up in the morning I heard a noise. Sounded like a faint piston slap? I continued and on the highway the noise has increased however it's louder than it was . And it was very consistent. Very loud but slowed down as I left off the gas. And almost sounded like a cam tic.i ended up driving over 100 plus miles to make it back to my home . The sound never went away or got louder or sounded like metal parts bouncing around . It was slow to crank and smelled like gas or some mixture of chemical but no overheating. So I started researching on YouTube tried to find all possibilities before I say the engine is gone from a spun bearing. I came across a video with a guy recording how it sounds to drive with a blown spark plug and it sounds very familiar. When I checked my wires just by glance not taking anything apart. I noticed they felt loose, the wires were loose and the boot that's behind or around the spark plug was loose I could wiggle some of them with my hand. I wanted to know if this was normal and something that might be causing this sound and if it could be fixed.