I took my truck in for routine maintainance and was told I needed an EFI Throttle Body service. Is this something I can attempt to do myself?

 

By all means yes. Get a good can of throttle body cleaner. Try not to use carb cleaner. Take off your air boot and soak the inside of the tbody and scrub it with a rag or old toothbrush then wipe it out. Your eng will crank a bit longer from all the cleaner in it but it will clear out