every now and then when i start my truck it does the first rev on start and idles down real low and revs up and again then idles fine and somtime when i start it, it revs up and drops rpms and cuts off and will continue to do this until you rev up a few times and it idles fine but you can smell gas like its running rich but it runs normal. not throwing any codes. this is on a 2003 f150 4.6L super crew king ranch. any ideas? thank you!

 

Try cleaning the idle air control.

 

yeah...I agree with bullit....especially if this issue only happens when truck it cold....(you restart warm truck and no issues)

check the mechanical function of IAC by disconnecting IAC from intake...leave harness plugged in and then have someone turn ignition off and on slowly a few times while looking inside IAC for piston movement...it wont move much..just enough to seal bypass (btw..you don't have to start motor when doing this)

if piston stuck...then clean out carbon buildup with carb cleaner and lube it with WD40 or something like that...unstick GENTLY with screwdriver (dont scratch piston)