What are best chemicals for EGR + intake clean?

Everything but the cooler: brake cleaner, with rags/brushes, will do the job. For the cooler only, a caustic cleaner is one effective route. I've used Oxi-Clean Versatile Stain Remover, a mildly caustic, powdered laundry additive, in a concentrated, hot tap water solution. Cork one end, pour in the solution, prop in the corner of a rectangular bucket of laundry sink, and after an hour rinse and repeat. With more modest build-up that's worked fine for me.

Don't use oxi-cliean or anything else caustic, on either the intake manifold or the EGR valve. The former has embeds that will react with caustic solutions, the latter is mostly aluminum which will turn the shiny valve pewter gray, and maybe mess it up as well. It's overkill anyway, again: brake cleaner is enough.

For heavier build up consider a lye solution, NaOH, carefully mixed with cold tap water. Read up beforehand, and be careful. Always add the lye crystals to water, not the other way around, wear gloves (eye protection doesn't hurt either), and use only glass and plastic containers/utensils.

A lot here also use a pressure washer, either alone or as a follow up to chemicals.

See top two links in my signature for more info. The second link in particular has cleaning tips. On a phone turn it landscape to see signatures.

 

I agree with Mendel on the brake parts cleaner and rags/brushes for most everything.
For the cooler specifically I had great luck with Dogman's suggestion of oven cleaner, then just followed up with garden hose.

 

Yeah oven cleaner can stand on for lye, it’s lye in solution in a spritz bottle, with surfactant too I think.

 

There was one poster who said he wanted to clean egr cooler but said nothing liquid that harms Mother Nature was to be posted. I said high pressure water sprayer and he cancelled my reply haha

 

Oven Cleaner: YELLOW EZ Off is lye in spray form. The other cans are not.

 

I could find no chemical that really worked well. I soaked it for a week with oven cleaner, carb cleaner and brake cleaner. My cooler was so clogged that I had to use my drill and a length of coat hanger wire. I have read that after many miles, the carbon hardens and requires more work to clean it. I tried to drill out every channel with the coat hanger wire. You should try chemicals first.