tweake is 100% on the money.
It is not even old school ..... it is the correct way, now and as it has always been. Remove the intake manifold and clean it out correctly. Have a vacuum cleaner on hand to clean the cylinder head runner as you will need it to stop loose carbon falling into cylinders. Vacuum out the intake runner in the head, then carefully poke a strip of cloth as far down as you can, loosen the carbon material and vacuum out the loose material. IMPORTANT .... don't forget to remove cloth plug you have put in.
"Some" cleaning systems "may remove" the loose oily deposits that are in the intake system however the caked on carbon will still sit there.
Blocking the catalytic converter or DPF is always an issue however more of a concern is running any loose material thru the engine cylinders.
While you are doing this remove the inter-cooler and flush it out as it will have engine oil from the breather thru the internal tubes.
Once you have done that fit a quality catch can/ vapor separator between the crankcase breather and the intake manifold and EGR blanking plate or restrictor. Warning ..... from an emissions perspective these plates are illegal and in some case's will set a fault code. Do your own research about these.
The caked up mess in the intake is a result of buildup of the oil vapor carried with blow-by from the crankcase into the intake and the hot exhaust gas from the EGR valve.
That should keep you busy for the weekend