Misfire at start and stoplights

Hey all, hoping you can help me figure this out without taking it to a shop...

1997 Ranger 4.0L 177k miles
Regular code on CEL is p0306 so Cly. 6 misfire
occasionally pending code of p0305 but it never actually gets logged.
Was original factory plug/wire/coil etc. up until last year when below occurred.

Recently replaced plugs, wires, and coil and all have been rechecked and swapped around without effect. The truck did have an issue last fall and overheated enough to shut down once. A replaced thermostat fixed that issue but I've been chasing misfires since then. MAF got cleaned and IAC replaced about 6 months ago too.

If i clear the code, it doesn't come back immediately. Also, I did a 4 hr interstate drive this past weekend and it never tripped while on the highway, but my first stoplight at an exit and it came right back on and idled poorly from then on till I cleared the code again for the drive back home.

I'm working on this as I get free time in the parking lot of an apartment complex without any other way to get to work.

Wondering what the recommended next steps are from you all. Thanks in advance

Welcome to TRS

I would start with a compression test just to take that off the table, otherwise you will just be wasting time, and maybe money, on non-fixes
Remove all 6 spark plugs and inspect the tips on each as it is removed, spark plug tips tell the story of the condition inside its cylinder.
If most have a light brownish color(Good) but #6 looks white and clean you may have a cracked head
The 4.0l OHV engine heads all have a weak casting between valve seats, if overheated the head metal expands and can crack here, this will cause lower RPM misfires and can cause air(exhaust) to be pumped into the cooling system.
Check if radiator is full to the top(no air) when engine is COLD, if not then it could be a cracked head, if it is full, then no problem

With all spark plugs removed do compression test
4.0l runs 9.0:1 ratio so expected psi is 150-160

But compression tests are more about the average and comparison of the numbers than "high" numbers
If #6 is running at lower numbers then you could have head or gasket issue.


Specific cylinder misfires can be cause by compression issue or spark issue
And since your 1997 4.0l is also running Sequential fuel injection it can also be cause by an injector issue.

#6 could simply have a dirty injector tip, so at lower demand, idle, fuel is Dripping from the tip not Spraying, so you get a bad air:fuel mix and misfires
Run a can of Seafoam or similar injector cleaner in the gas tank, that will clean injector tips.

#2 and #6 share the same coil in the coil pack, so if coil was bad both should misfire, but thats not always the case

Coil pack wiring is like this
3 4
2 6
1 5
front

They are arranged that way because they are Matched Pairs
3 and 4
2 and 6
1 and 5
Are each at Top Dead Center(TDC) at the same time, that's how a V6 engine is balanced, 2 cylinders at TDC every 120deg of crank rotation
Ford uses a Waste Spark system, so only 3 coils are needed for 6 spark plugs, #2 and #6 both spark at the same time, one will be on compression stroke the other on exhaust stroke, the one on compression stoke adds power to the engine/crank, other spark is "Wasted" hence the name

Try reversing #2 and #6 wires on the coil pack, see of misfire moves to #2 indicating a problem with coil pack

Thanks.

I've got some time off next week and will do the compression check then. The new plugs have always looked good but i'll get a better sense when they come out for the compression check.

I haven't tried swapping the 2 and 6 wires but will tonight and see what happens along with the radiator check in the morning. I had put a bottle of Lucas injector cleaner into the tank before the long drive so whatever it is, that didn't fix it.

Best case I can assume now is bad injectors, worst case its the head. Any thoughts on replacing either? Rockauto good enough or is there something I should watch out for with either?

Updates...

Checked the radiator and it had a bit of air in it but nothing dramatic, maybe 1/2" low at most.

Swapped #2 and #6 wires at the coil, cleared the code, and went for a drive. Never tripped the CEL, but I could identify a pending code p0300 and p0306 so something was happening.

Pulled all the plugs and started doing compression test and weather rained me out after getting 4/6 way thru.

Dropped it off at a trusted local spot and they skipped ahead to full shop rundown and narrowed it to my Cyl. 6 exhaust valve. They didn't want to replace the heads due to age and mileage. Recommended new motor but that's $$ I dont have.

So now my struggle is... do I just drive it till even more things start going bad and save up for the new motor in a year or two, get a shop to replace the heads, or start shopping for a replacement for lil red.

Any recommendations? It got a rebuilt tranny in 2013, new rear spring mounts in 2017, and the body has spent all its life either in a garage or in NC so rust is minimal. In my mind, a clean '95 4.0l 4x4 is worth keeping around as long as possible but maybe i'm wrong.

Mechanics are wrong about not doing the heads with 200k miles on the vehicle/engine
Bottom end on the 4.0l can go past 400k

If you can't do it yourself, call around and find a shop that will change BOTH heads.

Set of heads will run $400, gaskets and bolts $75, coolant and new thermostat, $40
Labor about 6 hours

If you have the time then heads can be removed and sent to a Machine shop, they can test heads, do valve job and resurface, for under $400, if a head is not cracked