Ok I have a 99 f150 with the 4.6 v8.I have a hesitation / missfire on my truck. I know something is up bc I can feel it jerking when I accelerate and when Im in a high gear its sluggish. No codes or check engine. Its been like this for about 2-3 weeks. I have changed the plugs about 15k ago and fuel filter as well as the fuel pump. Don't think its the invjectors or a vacuum leak or clog cats. I have not replaced the coils ever. And the wires for about 3+years. I'm running out of ideas please help.

 

Also I have 186.000 on the motor and trans.

 

186k on the coils... I would say it's time for new ones. Sounds like a low grade misfire to me. Good place to start anyway and to know you have new ones.

 

Ya at 186k it might be time to change a pack. I just had to change my coil pack at 165k because I up and lost #4 completely. That high gear issue is usually when you notice the misfire like 45 mph in overdrive under light throttle

 

Are you sure it's not the infamous mechanical lockup of the torque converter slipping? That shows up typically at low speed under light acceleration.