'92 Miata, surging problem, 85,000 miles.

Hi,
I bought this car used 2 years ago.  It had been left out under a tree,
and 
the drain line from the fuel filler well was clogged.  Rain overflowed the

well and went into the gas tank.  The seller drained the tank, and got it 
going.  I put some alcohol fuel treatment in it a couple of times and it
has 
been running fine until today.  I keep it garaged.  The symptom is fuel 
starvation.  When I step on the gas, the motor starts to die, and if I
lift 
off the gas, it smooths out.  I limped home 15 miles this way this
afternoon 
doing mostly 45 mph..
I'm going to start by replacing the fuel filter, and if that doesn't fix
it, 
also replace the fuel pump.  If 85,000 miles since '92 is about the useful

life of a fuel pump, I'll replace them both at the same time.  So my 
questions are: Am I on the right track, and is the fuel pump past its
useful 
life cycle?
Thanks in advance for any advice.
Mike