I have a V6 with 109,000 miles. It misfires right through warm up and is worse when I have to 'load' the engine. Idles fine.

This problem has been intermittent for the past 2 years. Done the plugs, coil pack, plug wires, injector cleaner and the code for a cyl. 4 miss comes up after the dealer has had it each time (in for the misfire and they replace parts and flush the injectors). The dealership says it is the injectors that have a slow leak, and they need replacing...they are NOT sure which one is leaking so they will have to run a test.

So my question is: Why are the injectors fine after the dealer flushes them for about 3 months, then get bad? Could I have a dirty gas tank?

 

You could check the injectors yourself, by removing them, and having a machine shop diagnois them(Pressure Test), or if you are unable to do that, have a second opinion outside of a dealer. Ask around and find a reputable shop, and it's not necessarily a chain.
I would hope this leads you into the right direction.
I don't believe you have a dirty gas tank, that problem should have shown up in your fuel filter.

 

Junior, the injectors on this engine I have are buried as far as I can tell (the independent shop that looked at it said the labor is in getting to them). I have a 4WD 4.0 OHY XLS Explorer. But one thing I haven't checked myself is the fuel filter. Can you point me in the direction of it's location? As I recall I need to depressurize the line? As you can tell I'm NOT a garage mech..

 

I apologize, but you are in the 4.2 Forum. A motor is a motor, but the configuration is different. I have a 4.0 as well in my Explorer, but I've haven't done much work to it. It has been quite dependable so far. I have replaced the T-Stat, and it is 10lbs of motor in a 5lb engine bay.I know that in most of my Fords I've owned, the fuel filter is along the frame on the drivers side, but you will need the spring depressors to remove it from the line, and they are quite inexpensive, $10 to $20.
You also may want to hunt around in the 4.0 Forum for more info.

 

Yep, as Greg noted, you have found your way to the 4.2/3.8 forum.
The general troubleshooting is likely to be about the same, but there are some differences in configurations.
We are glad ot try and help, but you might want to poke around in the 4.0 forum as well.
Thanks

ONTW, changing the fuel filter is not a big deal. It is likely located inside the main frame rail along the driver's side, near the door. But, I do not know for a fact on the Explorer.
Yes, you will need to depressurize the system. Not a big deal.
(Ask if you need details) and you will need the little tool kit (about $6) from your local auto parts place for removing the fuel filter.

Regarding not being a garage mechanic. Not to worry!
That's what keeps folks visiting FTE.

I suggest you invest in a Haynes Manual for your Explorer. Also available at the local parts store for about $12 or so.
Would be money well psent as it can help with many simple tasks, and some complex ones.

Stick around, we'll all try to help.