Need some wisdom!

02 Prerunner, 3.4, 286K. Last fall, replaced air boot, injectors (orig), fuel pressure regulator (orig), plugs, wires, coils. Cleaned MAF. Ran well.

Just now started barely running, very rough. Smoking (white). Fuel pressure was erratic around 42, but dropped instantly when shut off. Had all kinds of codes: 0440 type, 0300 type, 0171,172.
Replaced pump (orig), purge valve (orig) and upstream o2 sensor (orig). Tested coils w meter and examined plugs (photo attached)
Oil clean. Coolant clean. Fuel pressure steady at 42, but drops off fairly quickly after shutoff.

It's now a little smoother at startup, but becomes rough and smokes a lot. Ran codes, 302,304,306. I am mystified.

 

One glaring thing stands out. You're using single electrode plugs. Pretty sure that little white and blue label in your pic says specifically not to use single electrode plugs in favor of dual electrode.

I'd get some Denso/NGK/OEM dual electrode plugs in there. If you're getting misfires on the drivers side I'd be triple checking your wires are correctly connected to the coil packs.

After that I'd be looking to do compression test, and most probably a leak down test.

 

White smoke that won’t dissipate once it leaves the exhaust is coolant. I would have compression checked when having all the spark plugs out. You can rent a compression tester for free from almost any parts store.

I run single electrode spark plugs with no issues. 0300 multiple misfire code and 3 cylinders on the same bank won’t often spontaneously come up due to spark plugs you’ve had in it running fine for months.

All those cylinders are in the same bank. All this points towards blown head gasket. As the cooling system heats up, it pressurizes and can explain the rough running after the engine is running and coolant pressure increases to max.



But you still need to verify before proceeding.

This is an easy way to check for coolant getting into your cylinders too. You can also rent a pressure tester for free from parts stores. Check Amazon for any well reviewed cheapish borescope.

https://m.youtube.com/watch?v=CiwyPgrlbEM

 

cylinders #6 and 3 share he same ignition coil. I would swap that coil with another and see if the misfires follows the coil, if so, easy diagnosis. The one thing I do see is that cylinder #6 plug looks as if it isnt getting fuel or that is where the coolant is "cleaning" that plug. Pull the plug on #6 and start her and tell us if water/coolant squirts out, if no, then do a complete compression test.

 

He's got misfires on all cylinders in that bank. It would be hard to tell why with just switching one coil.