Hey y’all, I’ve had my 2001 ranger with the 3.0L for about 8 months now, it’s starting to get cold where I am and I’m having some weird misfires on cylinders 4&5. Cylinder 5 would occasionally misfire here and there but the engine always ran fine. Recently my check engine light has stayed illuminated which is abnormal. Cylinder 4 just recently started misfiring and I’m puzzled to what is causing it. Thinking it was a fuel problem I changed the fuel filter and the misfire is still happening. The engine runs fine until it gets to around 3500 rpms. Looking for some advice on things to check. I replaced the spark plugs around 185k miles and right now I’m sitting at 193k miles. Advice would be appreciated.

 

Maybe cracked coil pack ?

 

Welcome to the forum

Anytime there is misfiring that's repeated you should do a compression test
Changing spark plugs, wires and coil pack are just general maintenance, so that can be done first if all are older
But after that do the compression test to either take that off the table or find out that IS the problem, otherwise you will just be wasting time and money on non-fixes

ALL engine's get leaking exhaust valves, that's just part of the aging process on engines, when a leak starts to lower compression below a certain point you get random misfires, and the leak gets bigger and bigger over time so misfire gets worse, and then a steady misfire


If engine was stalling out(losing power) when over 3,500rpms, then yes changing fuel filter is another general maintenance thing that should be done, every 5 to 6 years usually
Next would be a Vacuum gauge test to see if exhaust is starting to get plugged up, i.e. Cats or Muffler internals have broken apart and are now slowing down exhaust from exiting engine
Neither would set single cylinder misfire codes, random misfire codes maybe