stop using cheap or the wrong grade of gas. use fuel injector cleaner and octane booster and that should do it.
It is possible that a part of the EGR valve has fallen out. This will cause a very loud exhaust noise.
Not that familiar with Jeeps, but you could have a collapsed lifter, or you might have a rocker arm out of adjustment.
The 2001 Chevy Cavalier may need a valve adjustment. Loud valves tend to create a clacking noise which could mimic popcorn popping.
I had a very loud humming noise coming from my 99' cougar. I talked to many mechanics and nobody knew what it was. I looked it up online and found two sources( listed at bottom) that said it was the idle air control valve. I replaced the part and my car runs great without the horrible loud noise.;
When a toilet makes a loud noise when flushed, it is usually due to a problem with the water pressure or the fill valve. This can cause the water to rush into the tank quickly, creating a loud noise. It is important to have a plumber inspect and repair the issue to prevent further damage.
Lack of oil lubrication to the valve lifters.
To minimize loud noise when flushing a toilet, you can close the lid before flushing, adjust the water flow, or install a quiet flush valve.
Your toilet may be loud when refilling due to a faulty fill valve or a high water pressure in the plumbing system. This can cause water to rush into the tank quickly, creating noise. Consider checking and replacing the fill valve to reduce the noise level.
Serious engine knock or valve train noise. Have this looked into by a pro.
ball joint or tierod end
The float valve shutting off the water flow.
It turns out that it was a bad idle air control valve. Right after I replaced it the loud noise stopped. About a hundred dollar fix, it was well worth it!