[B3NN3TT]

Okay. If I'm hearing this all correctly, the returnless fuel system on the latest Duratecs has all fuel pressure controlled by the ECU, and does not have a fuel pressure regulator, in the classic sense of the word. HOWEVER. There's a device bolted into the fuel line, just before the fuel rail, that certainly appears to be a FPR. Here's a picture:

There is a red vacuum line coming off the back of it that connects to the UIM. Based on the fuel system problems I've been having, I unplugged said vacuum line and sealed it off, which completely alleviated all my problems. To make matters more confuaing, fordpartsonline does indeed list a FPR for $30-some-odd-dollars, for all 99-02 Cougars.

So is this indeed a fuel pressure regulator, and if it isn't, then what the heck is it?

 

[B3NN3TT]

Okay, mystery solved.

After going to the parts store and looking at the FPR, it was DEFINITELY not that. So I went to the dealership, where they have the diagrams online, and we have found that its a FUEL INJECTOR PRESSURE SENSOR ASSEMBLY. $55 from Ford.

I'll update after it arrives and I replace it.