Hopefully its nothing serious, though. Failth that its something small and easy to fix. I hadnt ever come across a FLASHING engine light in a Ford before, so I wouldnt know where to start. Only knowledge I have is what I have experianced.
Just to add, if I may, I had a similar problem after I was working on the car [the V6] and I had only forgotten to connect my MAF sensor back in. Car was pretty bumpy 1st through 3rd gear though I dont recall a light going off. Im sure after running it awhile without your MAF sensor connected can throw a light on, but no one quote me cuz I havent been around a disconnected MAF for a long period of time, but Ill check everything electrical first, make sure it wasnt an easy DIY fix.
ALSO, there was a time I had some work done at a shop and after the car [the 5.0] was released to me, the car started to boggle a bit, then it almost rapidily gave me the light. I turned the car off for a few seconds, and turned it back on. Ran fine, light was off, then it did it again, light and all. I took it back in before the shop closed, and all it was was just a small vacuum line that they forgot to reconnect around my EGR. Ran fine afterwards.
Hopefully your problem is just as simple and cheap as mine were. Just when you have a few minutes, go look around, make sure everything is fitted tight and correctly and nothing was left disconnected. Good luck!! Let us know what happens!!