My 2000 Legacy EJ25 wagon recently started sputtering at low RPMs in slow traffic.  It finally gave out on me just off a freeway exit.  Pulled one of the 5+ year old platinum plugs and sure enough one was melted down like a used candle;  the rest were fairly fouled as well.  I will get fresh plugs and replace the fuel filter while I'm at it because it is past the maintenance period in age. 

Questions:

1.  I would like to try and clean a bit of extra carbon off the valves and combustion chamber before installing quality plugs.  I plan to use a spray can of Mopar combustion chamber cleaner directly into the intake with the car running as per this video: 

http://y2u.be/NDI6v8QeWVE

2.  I want to install fresh O-rings either way, but what is better: Clean or replace the fuel injectors?  I see they are about $25-30 each plus a core on RockAuto, and that's remanufactured.  Would it make more sense to replace the injectors with remanufactured units, or to clean them with one of those inline PEA chemical cleaning kits?  Or does it not really make sense to clean injectors if I'm going to run a PEA fuel additive through the system anyway?

Searched through posts and couldn't find much that was relevant or conclusive on these issues.  Hoping someone might have a clue.

Thanks!
 

 

Just change the plugs.

No spray cleaner is going to really do any cleaning of hard carbon on the pistons and valves.

And there is really no need to replace injectors either.  If they are working, no codes, normal fuel trims, etc, then they are working and replacing will just cost you money.

Spend it on a few tanks of premium fuel and you'll get just as good a result.

 I already got the plugs and filter swapped.  It's running good again.  Now that the breakdown is resolved, I'm inclined to agree with you; if it's not broken, don't fix it. 

By premium fuel, do you mean brand-name fuel?  Or higher octane?  Because everything I looked up on high octane gas suggests it leaves additional carbon deposits in engines that aren't designed to run high octane gas.  For example, this discussion:

https://forum.miata.net/vb/archive/index.php/t-235435.html

I've read other places talking about using water or chemicals at the intake, but I'm inclined to just throw some PEA based detergent in the gas tank prior to a highway-intensive road trip. 

After researching further, I'm inclined to use some Gumout Multi-System PEA cleaner in a couple tanks of gas per this Scotty Kilmer video:

http://y2u.be/gg9ppeUMpK4

I may even use an endoscope I have lying around as a borescope to check the pistons before and after the treatment.  If so, I'll post the pics here afterwards.

In my carb fed brumby (brat) I’ve used the water method. Take the car for a drive until it’s all proper hot and thermo fans are working. The drive is to heat all the internal parts rather than just the coolant as such. 

Then with some revs - 1500-2000rpm, I trickle demineralised water down the carb until revs are effected, let it build revs again and hit it again. I do this a number of times with the intention of creating a steam like effect in the cylinder to lift the carbon off the piston and combustion chamber. I couldn’t say if it actually worked or not as I don’t have pics etc. 

Cheers 

Bennie