Your problem is probably the ignitor module which is inside the
distributor.  Shouldn't need to replace the whole disty.  Go to the
Probetalk.com forums and research.  There is lots of info on this
problem including symptoms and various fixes.  It seems there are
inexpensive modules available, GM I believe that will work and are more
sturdy/reliable.

http://forums.probetalk.com/

Here is an example from the 2.5l V6 93-97 group:

$20 Ignitor Replacement/upgrade
This mod will save lots of people lots of money. It is also a good basis
for real ignition upgrades.

After 173,000 miles, my ignitor finally bit the dust. Not wanting to
spend $224 for another one, or an equal amount for a feeble MSD, I wired
in a $20 (Wells #DR-100) generic GM 4-pin HEI module instead.

In a nutshell:

The ECU's trigger output wire (BL/O) feeds the HEI's pin 'G'.
Ground the HEI's pin 'W'.
Ground the HEI's base.
HEI's pin 'B' taps into the +12V dizzy feed wire (BK/P).
HEI's pin 'C' taps into the coil's primary wire (Y/G).
Remove the internal strap connecting the old ignitor to the coil plug
center terminal.

I mounted the HEI module on a bracket next to the LH headlamp.

If $20 is too steep, head to the wreckers and get a used module for a
buck or two. Almost every GM car from the mid 70's to the mid 80's has
one.

If you don't want the stock coil, it would be just as simple to use an
external coil if you add the extra terminal to the cap for it. Lotsa
places have hi-perf. HEI modules and HEI specific hi-perf. coils too.