'98 Blazer won't start - eats ignition modules

I have a '98 Blazer with the 4.3L engine. For about 1 year it has been running very rough, especially when it is damp outside and it has sat overnight. It usually will run well after about 30 minutes or so.
It has also gotten so bad on 3 occassions that it won't start at all (cranks but won't fire). If the ignition module is replaced, it will then start. Something appears to be taking out the ignition module.
I have replaced virtually (if not all) every ignition component within the last 6 months, including plugs, wires, cap, rotor, module, coil and even the TPS.
It is now dead again, and this time after a shop replaced the module. It is interesting to note that the mechanic said the base timing was way too high as well.
Any suggestions are very welcome, as this is getting pretty bad.
The truck has 104K on the clock.
Thanks,
Jeff
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from water damage. Google for a solution, like maybe some water diverter or such. And check for good grounds, grounds, grounds.....HTH, s
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