'95 5.0 GT Mustang engine stumble and splutter - Please Help.

Hey Ya'll

I'm having some real problems with my 1995 GT Mustang (5 speed).

Some history, recently my power steering started leaking and the pump
actually ran dry, but I remedied this situation by running some power
steering sealant through it and that problem has gone now... but almost
at the same time I've started having some issues with the engine when
it heats up (this doesn't happen when the engine is cold, and seems to
get worse as the engine gets hotter and hotter.)

What is when I'm driving along (no matter which gear I'm in) if the
revs are between about 1500 and 2000rpms (but never below 1500rpms)
then it starts stubling and hesitating, the revs drop momentarily but
then pick back up - so the car is drivable (ie it can drive 30 miles
before you go nuts) but it's very unsettling. It also seems to be
knocking when this occurs.

I had a friend look at it and we decided that it seems like a sensor
problem, initially I thought it might be the fuel filter, he plugged in
his computer to it and it threw two codes:

- One about the SPOUT being grounded or something (#212), and
- One about the Fuel Pump circuit (#561 or #567 - we think)

(I really should've written down the exact numbers but I never thought
about it at the time I called him and I've added the numbers above)

One other point I should add is that when we plugged in the computer
the EGR did not show a reading, I'm not sure whether this could be
causing the problem or not and if it is how to better diagnose and then
fix it.

This is really bad timing for me because I normally ride my bike to
work but with winter coming I need to get the GT running and fast, I
hope I've given enough info to get a started but will answer any
pointed questions as best I can.

Cheers,
Sam.

sounds to me like you are losing fuel rail pressure. have you tried
changing your fuel filter?