My 2005 4x4, 5.4 liter is making a ticking noise in front end. The noise does not occur when the vehicle is stopped. The noise gets louder as speed increases and stops when put into 4 high... Swap back to 2 and sometimes stops... Any ideas???

 

Could be the 4x4 hubs. Mine did it. Low vacuum will cause the hubs to chatter if you loose vacuum pressure in the 4x4 system. Mine was a leaky hub and bad check valves. The system uses vacuum to disengage the system and drops vacuum when engaged

 

IWE Solenoid... Problem fixed