No compression/engine light on/engine stalling/etc.

I have a 2001 Ford f250 super
duty, 315,000 miles. Here's my
problem: about a month ago my
truck started losing power and
compression ( same thing?) after
driving only a few minutes. It
would gradually lose power and
Max out at 2000 rpm's within that
time. The more I tried to give it
gas it would lose power 2x as
fast. Basically it produced the
opposite effect. If I kept driving it
it would quickly become so
difficult to accelerate that I was
unable to maintain even the
lowest speed limit until the truck
engine light would come on and
then finally die. Although after
only a few minutes later I'd start it
back up just fine. But pulling out
again the problem started
immediately. Now (4weeks later) I
can't even drive 20 ft before the
truck stalls out and dies. Still
starts up fine. But can't go faster
than 5mph. I'm thinking it's the
fuel pressure sensor or the
injector pressure sensor. They're
the same thing? I've never dealt
with this before so any imput is
welcomed. Also wondering if
sensor is inside the fuel tank or
not?? Thanks