Please help no service place can fix my problem. Took 2006 F150 5.4L in for tuneup with plugs due to lack of power, had 105,000km on it. 3days after plugs changed got a misfire on cyl 7, 2 days after that got a misfire on cyl 2. Replaced coils to both and plug on cyl 2 as the platinum tip was burnt off (tech said due to faulty coil) but he also put what he said is a cooler running plug in it just to test. well less then a week later hear an interesting rattle from under the cab, took it to a different dealer (lack of trust with the 1st one) and turns out my CAT is fried, due to all the misfires. Replaced that. So on my way home got a misfire on cyl 5 not 3 blocks from the dealer? Any ideas on what could be wrong? I am thinking it cant be injector because it is a different cyl all the time, same with coils, no chance they would all be faulty at the same time? Only thing I can think of is original tech put wrong plugs in or gapped them incorrectly? Please help.

 

55 views and no ideas? Please help I am lost already shelled out $2000

 

What supplies the coils their voltage? Almost seems like an ignition issue.

I'd be inclined to check the fuel pressure too. Your individual injectors aren't all failing at once.