Mine connects with WiFi.

 

Ok WiFi can process a higher data rate, over a longer distance without data droup-out, so turn Off the cell phone on the next test drive, in case it messed with things somehow.
I forgot to say, If you hear the crackling sounds again, without delay pull over in a safe spot & check the cat converter to see if its being over heated / glowing red. If so, try & avoid that drive cycle mode until you determine the cause & put the fix on it, as overheating isn't doing good for the cat converter.

 

DATA REVIEW: Looking back at the #2 cyl spark plug photo in post 55 & the FORScan misfire data it logged for cyl-2 in the earlier post 42 screen shots, we can Now get an idea how sensitive OBD-2 diagnostics is & what those diagnostics & FORScan was trying to tell us to ckeck. Why it was detecting a misfire on a cylinder you didn't have a trouble code for Yet!!! We just have to learn how to interpret & trust what diagnostics is trying to clue us in on!!!

How are the test drives going after the XP104 plugs were installed???

 

Well, I haven't done any really long freeway driving yet, but I've started pulling a trailer, and done a fair bit of freeway trips under 10 miles each, and so far it seems to be doing fine.

I think my next project is to replace the cracked fuel fill pipe so that I don't loose a couple quarts of gas whenever I fill up.

Thanks for all your help!

 

Ok good feedback & to hear its improved more with the specified design type & heat range spark plugs. Don't forget to replace the hard / baked out PCV hose, so Murphey's-Law doesn't get a chance to seize an opportunity to have its way with you, like it did with #2 spark plug!!! lol
Continue on with getting all past & present due scheduled maintenance items replaced, with items that say in writing they meet or exceed Fords specifications & it may yield many more trouble-free miles.
I'm working on my 99's, 90K scheduled maintenance & its a biggy list!!! Fluids, filters, plugs, wires, grease inner & outer front wheel bearings, you name it, its likely on the list.
Bet most following this thread have never re-greased the front wheel bearings every 30K miles as called out, or flushed the brake, tranny, or differential fluids.
Probably take me the remainder of the year, but I'll get-er done!!!

 

If the fuel fill pipe is cracked bad enough to leak that much, it'll mess with the emissions vapor recovery system & may set a Gross vacuum leak trouble code & its a fire hazzard, so I agree with putting that at the top of the "do next" list.

 

Ok, good feedback on it seeming to be freeway running ok & with some towing too. Sounds like you may finally have a good grip on the higher rpm intermittent freeway miss, with the new fine-wire spark plugs.
Continue on with getting All past & present due scheduled maintenance call outs up to date, so you know what you have as a baseline.

If this is a manual tranny 4banger & you haven't gotten around to it yet & are beginning to tow, be sure to check, or better yet with the mileage & unknown maintenance history, change the tranny & differential lubes. If the tranny lube is low, while your under there, check the manual tranny rubber shift rail plugs to see if they're dry-rotted & weeping fluid. Those plugs dry-rotting & leaking fluid has caused a number of tranny failures. Good luck on your vintage Ranger resurrection.

 

Update on the misfire situation. Yesterday I drove 200 miles at about 60mph the whole time (my best fuel efficiency speed), and had zero issues with misfires. I did not have the forscan hooked up, so I possibly had one or two, but to my ear, the truck ran perfectly. No codes either.

Since it was the last thing I changed, I believe the spark plugs may have been the thing that finally solved the issue. Thank you everyone for your diagnostic assistance!

 

Good feedback on a good long highway run, so I'd tend to agree, sounds like you've put the fix on your under load, high rpm intermittent miss.