96 4.0 cyl 4 missfire...help

[my90bird]

changed plugs,wires and coil pack.still sets the code off for cyl 4 missfire.idles rough but seems fine when driving normal except for power loss when I floor it but only some times.can anyone suggest anything to try next??

 

[team]

do a leak down and compression test to see if that cylinder is bad compared to the others. If it is the same as the rest then you could swap the number 4 fuel injector with another cylinder and see if the fault code follows the injector.