What Bert said.
You may need to clean the throttle body too. Check for vacuum leaks- 4.6l aluminum intake has a rubber "T" near the throttle body on the right side and a short rubber hose on the left of the throttle body connected to a hard plastic vacuum line.
May need to replace IAC if less expensive attempts yield no results.
Further consideration is fuel pressure. Regulator- Any black smoke from the exhaust? Pump itself- Hook up a fuel pressure gauge to the schrader valve on the fuel rail. Does it hold about 40 psi? If not you may have a weak pump or a faulty check valve in the pump.