You will need to remove everything from the UIM to thoroughly clean it. There is a tube in the UIM casting from the EGR boss over to the throttle body. Run something through it to clear it out. Be sure to dig the carbon out behind the throttle body gasket area. Many posts on this.
Get the intake gaskets, throttle body gasket, EGR gasket, and IAC gasket. The EGR valve itself rarely causes a problem, and is easy to get to at any time. Clean only if lots of buildup, and by scraping with hardwood.
Be sure to read:
Intake rebuild This may not be the current problem, intake leaks usually cause driveability or cold weather problems. Better to do it before it strikes, and doing work on the engine may trigger the cracked and dry rotted seals to break anyway.
