Rought idle in Park after warm up

[liquidxtassy]

hey guys bought myself a 02 audi a4 3.0 and i have a problem....after its been warmed up and ran a while when i put it in park the car starts to drop rpms and then rise again and wont stop unless i give it a little gas and it levels out or i put it back into drive...can i any one help and maybe figure out what the problem is? i would appreciate it.

[diagnosticator]

Erratic idle is often caused by a dirty throttle body. Cleaning the TB is the first thing to do.