If it is, If I remember it's part of the lighting control module.. $400 as it has many relays for the lights.... Under the dash and to the right of the gas pedal.... If not should be a yellow relay somewheres on the drivers side usually.. Ford dealer will tell you for sure in their parts book...
HOWEVER.. I think your issue is NOT the relay.. I work on them and never replaced one yet on a non police unit yet...
You are probably having issues with the turn signal switch which is a known issue and can cause exactly what you are describing... beating on the switch sometimes makes it work again... But replacement is best option