I'll try to be brief and share the background so you can help me find the hidden issues....
Bought an old 2006 Ranger Sport 3.0L V6 from a floridian who moved to Texas. Truck looked great, no visible issues (engine bay had been professionally cleaned so I was looking for anything) and really didn't see much rust anywhere at all.
Radiator cap had leaky seal, oil cap was not burned inside, new filters (air and oil and fuel), new battery. Started up immediately though it had a shimmy badly and a check engine light. ODB2 port was dead (bad fuse) so I had to trust my gut that it wasn't anything unfixable. For once I had a ranger that had working airbags, heater worked, dash was intact, all of it looked good.
Only warning bell I really saw was water in the light bar (opening in between fog lights) but I dismissed as could be the guy that washed it got happy with the power washer.
Drove it home and started immediately cleaning and swapping sensors and fuses. Got the ODB2 port working:
P0300 (random misfire) and
P0302, P0303, P0305 (misfire in cylinders 2, 3, and 5),
P0420 and P0430 Catalytic converter efficiency below threshold bank 1/2

Replaced Mass Air flow, O2 sensors, Idle Air Control valve, cleaned intake and throttle position, replaced sparks, wires, and coil pack for good measure, Noticed while doing all of that alot more rust and "gunk" - like river "gunk". I think this truck was driven in rivers or on the beach. Cleaned out the light bar (removed the glass and resealed it after drying) and it was mossy green algae water.
Alot of corrosion on alot fo the connectors so I went to cleaning wires and connectors and putting dielectric grease where needed to protect. Replaced the low-freq horn... it was full of nasty water. BUT after cleaning up all the "gunk" I could, I cleared DTC codes and took her for a light drive.

MUCH improved but still kept having a misfire in cylinder 5 but ONLY when it was idling. Literally used my ODB2 logging to try to visualize it:


Red - misfire only when green (speed) and yellow (load %) and blue (RPM) show engine is idling.

SO since it was only on the light load and not driving, I suspected clogged injector. Ran some seafoam, then tried out a few different injector cleaners. Seemed to work really well, thought it was getting better and better!
UNTIL... one day I notice a rattle while accelerating. Soft at first but then got worse and worse. Finally pulled over and shut it off. googling and chilling to make sure no issues would be permanent if i kept driving it the 10 miles back home. Would NOT start up. Cranking and turning over but wouldn't start. Took about 10 minutes of trying repeatedly, then wait 30-60 seconds and try again. Finally got it started and it rattled to high heaven.

Thought I blew it out! She died twice on the way home, both when turning into the neighborhood (around 8MPH) and once turning into the driveway. Didn't even make it into the garage.

Next morning I checked, no fluids underneath. Oil looked (a little dirty) but fine. Radiator reservoir has bubbles after driving a bit - but the heat is gone so I suspect a bad heater core. no sign of coolant or oil mix. BUT the truck started right up. Thought, was it bad gas? too much cleaner? It had about a quarter tank left so i went to gas up with highest octane I could. BARELY made it to the station (around 1 mile). Stalled once on the way back too. Checked the codes.

Check engine now says P0171 and P0174 (System running Lean Bank 1/2). And now it is misfiring on 2 and 3 and 4 again!
Wondering if the cleaners got some junk stirred up in the tank so its clogging stuff left and right? or maybe blown head gasket afterall? I did remove the fuel rail Shrader valve stem and then jumped the fuel pump relay to have it pump out all the fuel. All came out clean (gonna use that for mowers I guess and put new in next time I drive). BUT I noticed that it had NO pressure when I took out that valve stem. So could it be the pump? Or could it be a bogged up catalytic converter?

I have no idea where to go from here.

 

Replaced fuel pump, fixed radiator cap leaking. Then drove it and got the knock WAY worse. It died and hasn’t started since.

NEW symptom… when I filled up the radiator to the top now it is actually pouring out the catalytic converters! Both of them have a very steady stream of coolant. What the heck….

still no coolant in the oil, but need to know where to begin!



best photo I could get, verified no leaks above, no trails from anywhere, not even down exhaust it is inside the exhaust itself.

 

Replaced head gaskets and got the heads machined. Truck runs fine now. Replaced heat temp sensors (x2, no sender just two sensors) MAF, idle air control, throttle position sensor, all wires and plugs, sparks, water pump, flushed coolant twice, fuel filter, and fuel pump.

last issue is a P0171 - system lean. No other codes so don’t expect MAF. Couldn’t find an air leak yet on intake side. Previously replaced O2 sensors, so now thinking fuel pressure regulator. Anyone have thoughts?