1999 Ford Escort

Engine Performance problem
1999 Ford Escort 4 cyl Front Wheel Drive Automatic 91000 miles

I have a 1999 ford escort se, and sometimes it idles really high, and shifts super hard. But sometimes it wont start at all, so I had it hooked up to a diagnostic machine and it said I need a fuel pressure sensor, I called to get one and aparrently there are two different ones, one in the tank and one on the fuel rail, how do I tell wich one I need, or could I just need a fuel pressure regulator? I need help!
July 2, 2008.

Check the fuel pressure before you start buying unnecessary things. You might just need a fuel pressure regulator-I've looked for the fuel pressure sensor there's no listing having it-however there's an injection pressure sensor near the fuel injector no.1 on top left front of engine

Jul 2, 2008.