Hello, I'm going to try my best to give you as many details as I possibly can here..
My truck is a 2003 F150XL 4.2L V6 2WD automatic, manual windows/locks/etc
VIN# 2FTRX17253CA12755
Mileage approximately 225,680 ish
It has an oil leak (pretty sure coming from the oil pan gasket and/or oil filter assembly gasket)
Fouls plugs every couple months (white ash buildup)
Most recently the engine began shaking, loss of power, throwing a blinking "check engine" light. I stopped the truck as soon as I could. After diagnosing with a friend I R/R the coil pack (one coil pack controls all plugs). In diagnosing we:
°checked code - misfire on #5
°swapped plugs
*no change
°checked spark from wires
*no spark on #5
°swapped working wire to #5 on coil pack
*no spark on #5, previous wire was now sparking fine on new connection
°installed new coil pack

That fixed the problem for a week. Truck ran fine until I left work on Wednesday. It, again, began shaking violently however didn't throw "check engine" light this time. I pulled over immediately and got it towed home. In diagnosing this time we:
°checked codes
*misfire #5
°checked spark on #5 wire
*no spark
°checked spark on #5 of NEW coil pack
*no spark (seems odd that it would be an identical issue with the new coil pack. To me, this is a trend)

I thought about swapping for better coil pack and wires BC I tend to buy the cheapies (225+k miles - I tend not to want to put more money into this except when absolutely necessary) but I'd really rather not throw parts at the engine without any real ideas about what is causing this tiring trend.

Any ideas or insights would be greatly appreciated!! I'm, thankfully, not in a rush so I will not be making any forced snap decisions.
Thanks, in advance, for your help!!

 

I'm going to ask you to extend your thinking one more level.
What tells the coil to fire in the order?
Assuming you are accurate with the info, your code might be a 355.
Yes or no.
If yes, the coil is not being ground pulsed by the computer for that cylinder.
Is the harness to the coil open, the plug not making good contact at the coil, in the harness back to the computer or the computer has a fault.
.
If no, your code should be a 305.
That means the issue is at the cylinder.
Bad plug, fuel injector blocked, a fault within the cylinder.
.
More info; a fluff grey/whitish spark plug tip is normal. If crust accumulations,
they are the chemicals deposits from the gas your using.
A fouled plug is generally thought of as fuel fowled, carbon deposits or oil soaked preventing firing the cylinder.
What code and condition do you have.

Good luck.

 

The code that came up was po305. I had an idea that the injectors might be clogged because of the fouling plugs but still don't understand how any of the 305 problems you listed could cause the wires and coil pack to fault and become unusable.
I don't consider myself an actual mechanic, more shade tree and I try..
Also, to further explain buildup on plugs (sure wish I saved a picture), it's a white buildup that takes over the entire end of the plug creating no gap whatsoever and it is extremely hard consistency - unable to wire brush or sand off even with the help of carb cleaner/starting fluid.
Think you can detailed explain next action I need to take to fix or diagnose my problems?
I sure do appreciate your help!!

 

Re read the last half of my reply for the 305 code.
.
You have an issue from the coil to the cylinder for some reason.
Either a plug wire, spark plug, or a cylinder issue.
.
A plugged injector meaning no fuel dispensed, cannot foul a plug but sure results in misfire if there no fuel to combust in that cylinder.
.
White hard deposits is chemicals in the gas that form on the tip from high heat of combustion.
Only way to reduce that is change gas suppler and or change plugs at an interval before the buildup goes too far.
.
If you have replaced the coil, the plug wire and the plug, do a compression test of all the cylinders to compare #5 to.
.
NOTE; How the system detects a misfire:
The Crank Sensor measures crank rotation time for every cylinder on a continuous basis. If any cylinder rotation time falls below a limit for the average of all the cylinders kept as a floating record in the computer program, it is considered a logical misfire, in computer terms.
.
Good luck.

 

Thanks for the info!
Will try compression test tomorrow as it looks like I'm putting in a max DOT day today..
After that, I guess I'll swap wires and coil pack again - have to anyway since coil pack is blown.. Gonna probably get an upgraded coil pack rather than the absolute cheapest. Dunno what else to do on that front.
Also, I'll try fueling up somewhere other than Wawa which is where I've always gone with this truck.
Thanks again. I'll update after I work on it tomorrow. Then, again, if I run into the same issue in another week..

 

Compression is as follows:
3 - just above 180
2 - 180
1 - 180
6 - just above 190
5 - 190
4 - 190

R/R upgraded wires
*Autozone said they're the ones that come on these trucks from the factory
R/R upgraded coil pack
*Looks like the original

Truck fired up and is running well currently.

I'll add another reply if it messes up again.
Thanks for your help