how to tell if idle control vavle is good 1995 5.8
 

How do I tell if idle control vavle is bad? I took it off and could blow air between the 2. I figured when valve was shut offf it would be shut so air wouldn't go between.

Best way is to hook a scanner up to the truck and run a Key On Engine On(KOEO) Test. This will activate the IAC (Idle Air Control) motor and tell you if its working.