4.0L misfire

[ranger240]

i have a 99 ranger with a 4.0L that is running really rough at idle and even at cruising speed with no change. i have changed plugs, wires, and coil pack with no change. the check engine light is on now and the code that comes up is for a misfire in the number 4 cylinder. i have tried moving wires and plugs around to see if it would change where the misfire was but it still remains in the number 4. i have read all kinds of ideas about the throttle body position sensor and the MAF sensor but have checked and replaced both so im stuck!! i need some more help but dont want to just throw money at it.........any help would be greatly appreciated

 

[campermama]

OMG! read my posts.....you need to pull #4 spark plug and look at it. I had the same thing and turned out it spark plug cross threaded going in and messed up the plug. I really hope for your sake this isn't what happened to you, we are in the middle of pulling the engine to fix it. Let us know!

 

[mlunsford]

Had Same thing

My turned out to be cracked heads (both). Cracked between the valves on 1 and 4.

Try a leak down tester and watch the radiator for water to come out when the test begings.

I saw leak down tester at Harbor Frieght tools for $30.