Some of this may be a little OCD, but I also know some of these things could be very helpful. I am pulling my 3.0 for a rebuilt one (I know...shoulda done 3.4...sorry). While I have it all out, I would like to clean it up for performance reasons as well as some aesthetics. So how would I clean the following:
1. Intake plenum and lower manifold - do I clean that myself or take to a shop for some sort of steam/boil cleaning?
2. Heater core - not leaking and working well. Just seems like a good time to do something with it while truck is being torn apart. Better to leave it alone? I will have the A/C evap out anyway due to a leak in there.
3. Timing belt cover - typical faded, gray looking plastic. Is there a good way to spruce this up? Maybe some of that Fusion plastic spray paint? Some sort of dye or silicone wipe?

I'm replacing basically every hose in the bay. Some of the custom fits are pricey, but seems the time to do it. Any other items I should be inspecting/replacing while the engine is out?

 

For the plenum, a good degreaser (I like Purple Power) and an ordinary bottle brush will go a long way. You'll want some contact time for whatever cleaner you use, so I used a mortar tray https://www.homedepot.com/p/Medium-M...6100/301943161 to contain the mess. Purple Power is reasonably safe, but it has a pretty high pH (12.98!), so it will eventually etch the machined surfaces of aluminum. I wouldn't leave aluminum in contact with Purple Power overnight.

Bottle brushes won't reach everywhere inside the plenum, but if you can't see what's missed, who else can? You could remove the end caps of the plenum to get inside; they're just standard freeze plugs. I didn't do that; I'm now conflicted about whether I should have (more thorough cleaning vs. small risk of damaging the aluminum by removing the caps).

Replacing every hose is OCD. As you know, the formed hoses are pricey (and don't try replacing a formed hose with stock straight hose). Hoses usually don't fail catastrophically (they'll leak for a bit), so you might consider keeping all the good-lookin' hoses that are accessible, and only replace the more worn hoses plus the ones that are pretty inaccessible.

Take pictures. If it goes as well as you plan, you'll want to come back here and brag.

 

When I did my 22re intake manifold and valve cover, I pulled all the sensors and rubber hoses off and used oven cleaner to remove all the carbon and oil/grease. It worked great but it can stain the aluminum dark if left on for too long without rinsing it off. It wasnt a problem for me because I was painting them anyway. Probably not the best method but it worked for me.

 

I cleaned my 22RE valve cover with WD40 and a wire wheel on the drill. I have a pretty large ultrasonic tank and I tried putting the valve cover in that(about 1/3 fit) and that made no difference.
I wouldn't paint any plastic. It just doesn't hold up and It'll look terrible in a short amount of time. You can try using a heat gun and carefully move along the surface. Just don't distort it. I'm sure there's videos on Youtube showing how.
I've heard of some using electrolysis to clean alloy wheels, but even for me that was getting a little too carried away.
I cleaned my trans/transfer after rebuilding using WD40 and the wire wheel. the only thing I painted was the black adapter plate:

 

You're on the right path, and are doing a great job. That new long block will make you smile for years to come and is worth supporting with new small parts around it. I'm with you on replacing all of the hoses and did the same thing when I did mine. Don't forget the fuel injector cups too. If yours are like mine were, they are fossilized and would be a great place for vacuum leaks when you re-install. On the plastic timing cover, I hit mine with flat black rustoleum with a clear coat over it. It still looks good after a year. You can wire brush the aluminum plenum and clearcoat that too. New clutch while you're in there?

 

Thanks for that! I actually replaced my injectors about 2-3 years ago with the yellow Flamethrower 4 hold variety and have been pleased with them. New cups when I did that. Also replaced the clutch, flywheel, throw out bearing, etc about 3 years ago with a Marlin Crawler heavy duty kit, so I’m thinking I will leave that alone, assuming it all looks good. I do want to look at the tranny input seal (correct term?) while it is apart. That’s all I can think of down there.
thanks for the cleaning and painting tips. I will just do some light scrubbing and a little chemical cleaning. Not too worried about it, just might as well clean it up a bit while I have the chance.
Just picked up the cherry picker so now the fun begins.