im hoping that your talking about a truck .... but if your wondering about
a high idle it could be a few different things... there is either a
vaccuum leak somewhere like the elbow running to the pcv valve is common,
it could also be that the ignition timing is out. i would check all of the
hoses running from the throttle body for leaks, pull out the idle motor and
clean it with a throttle body cleaner and see what that does for you. if
nothing happens or you find no leaks try checking the ignition timing
make sure the zero timing wire is disconnected its a tan wire on the
firewall near all of the relays under a black cover**
with this wire
disconnected the timing should be set to 0* then reconnect the wire...
thats about the extent of my knowledge without seeing the thing running in
front of me so good luck!