Hi, I own a Laredo 2006, due to an overheating that caused that the Jeep pauses, him change the thermostat, but apparently this not working a cylinder. They already changed the game of spark plugs and persists the problem.
Help me please, what can be the problem ?

 

If you over heated the engine, then it is a good chance that head gasket is blown. The head can be warp or crack too. Does the oil get "milky" ?.
You need to perform compression test. If you take the plugs out, look at which one is black or wet.

 

What happen with the black or wet ones?

 

black mean too much fuel. Wet mean too much fuel or low compression. Put the compression gauge on that wet one. You should have at least 100 lbs.My have 125 all.