Due to the ease of installation and relatively high cost,   we would recommend replacement only when necessary and not simply as a preventative measure during the 60K/100K service.  

Many supposed DIS module failures are simply insufficient grounding.
Be sure that your existing module is properly grounded through it's mounting bolts,  and also be sure that the intake manifold end tank/crossover tank is also properly grounded through it's two mounting bolts.
The DIS module should have a thin layer of heat-sink paste on the back. 

Typical symptoms of failure can include misfiring,  stalling,  and rough running,  but of course these can also be caused by other issues.   Usually a trouble code will be set during failure,  causing the "check engine" light to come on.
If you're troubleshooting a driveability issue,  always start by checking and diagnosing the stored diagnostic trouble codes.

"The ICM (ignition control module) receives the CKP signal from the crankshaft position sensor,  the CMP signal from the camshaft position sensor,  and the SPOUT (spark out) signal from the PCM (computer).
During normal operation,  CKP is sent to the PCM from the crankshaft timing sensor and provides base timing and RPM information.
The CMP signal provides the ICM with the information required to synchronize the ignition coils so that they are fired in the proper sequence.
The SPOUT signal contains the optimum spark timing and dwell time information.
The spark angle is determined by the rising edge of SPOUT;  this is when coil current "turns off" and spark occurs.
The dwell time is controlled by varying the duty cycle (duration) of the SPOUT signal.  
Current flows in a coil (dwell) when SPOUT is "low".   This feature is called computer controlled dwell (CCD).  

With the proper inputs of CKP, CMP, and SPOUT,  the ICM turns the ignition coils on and off in the proper sequence for spark control."