Much easier to remove the intake manifold - it's dry - no coolant involved - fairly easy job start to finish, and you'll be able to do a very thorough throttlebody cleaning in the process. Use a couple of old toothbrushes and lots of rags. You cannot clean the inside of the manifold itself, so accept that; it's not critical anyway. While you're in there, disconnect the battery and double-check the starter mounting bolts and electrical connections. The manifold is a glass/plastic composite, so go easy on the bolts - 89 in/lb of torque - about 7.5 ft/lb - not much. Double check the PCV clean and dirty air piping - if it's cracked or connectors are decayed, replace it all with vacuum hose from a parts store or NAPA.