I had the same issue with my 06 fx4 with the 5.4 changed all plugs and coils problem solved. I stuck with motorcraft plugs and used accel coils p/n 140033-8 and they work great. And they're cheaper than oem coils

 

I replaced one coil in June with OEM. Now they're all bad except the new one. (118k, replaced plugs in March) I just ordered a set of the Accel's today. Hope this works.

 

X2

 

My 1998 F150 had a similar problem. I gave it a new set of plugs and cleaned out the grease and oil in the plug sockets and also fixed a anti freeze leak at the heater hoses (new hoses and clamps). Also cleaned the plug wires. When I put it back together I put anti seize compound on the plug threads. On all the wires, at the spark plug and coil connections, i put Permatex Dielectric grease at the connections. Also put it at the connection where the wiring plugs into the coils. Have had my truck for 5 years and it has never run better even though I have tuned it up before. The Dielectric grease was purchased at Autozone and cost about $4. Well worth the money.

Did other things, not sure this made a difference.

Changed the fuel filter

Installed a new speed control (found out this sends a signal to the computer telling it how much fuel it needs from the fuel pump.) Mine was giving me a bad reading at the Speedometer.

Good luck and motor on good buddy

Frank_Ford

 

Same things happen to me, I get the occasional misfire when turning it over, probably 1/100 times... No codes are thrown at all so it's impossible to target the exact faulty coil. Going to replace all of them in the near future.

 

Is there a way to test a coil? Or to test cylinder misfiring? I Also have no codes...