I don't work in auto sales, but I have friends that do, this is what I'm told. When you go in they ask you "where do you need your payment to be" as normal, we tell them what our payment is currently and or what's the most we will pay. Well at that point you just got your payment, the most you can pay! Also in the financing, when they, financing, enters your info they get back several offers from credit companies ( again what I'm told ) the finance person is gonna approve you at the highest rate that fits that payment you told them in the beginning. Example, if you told them you can afford a $600 monthly payment, and they get you approved at $610, at 11% interest, there's a good chance they have you approved at a lower rate and a lower payment. Again this is what I've been told and learned over the years, nothing wrong with that process, after all we told them what we could afford!
I would most certainly go back and try to see if Ford credit will beat the WF rate of 9. I'm self employed, I have had my share of issues over the years, I have always used Ford credit, Ford credit has been amazing with the deals they have done for me, because I've been a faithful ford guy and always used ford credit they appreciate that and are willing to work with me.
Don't be afraid to haggle, they expect it, if you want the car, make the dealer earn your business, they want to earn it!