It could be your timing is off or your timing chain needs replacement.
Tune up
if it only backfires when shutting off, usually this means its getting to much gas!! if it backfires will running adjust carburater.
Check your timing and your vacuum advance.
Time for a tune up.
It backfires because if you are going high speed and then suddenly let off the gas the extra gas that is flowing in has to come out some time another way it backfires is that something on the exhaust or carbeurator is loose or is missing something.
P0400 Exhaust Gas Recirculation Flow Malfunction LIBERTY DOES NOT HAVE AN EGR SYSTEM. P0400 DOES NOT APPLY TO LIBERTY
check or change the spark plugs & wires
The 2010 Jeep Patriot is a gas-powered vehicle.
The 2014 Jeep Wrangler is a gas-powered vehicle.
The 2009 Jeep Wrangler is a gas-powered vehicle.
The 2011 Jeep Patriot is a gas-powered vehicle.
The 2010 Jeep Wrangler is a gas-powered vehicle.