Here is the problem:

I have a 1997 S10 Blazer 4WD with a 4.3L...I recently had the battery go dead and changed it. When the battery went dead and I replaced it, I noticed that the overhead trip computer with the temp, direction, gas mileage etc., stopped working correctly and the engine has begun to sputter and miss. It first started out having occasional issues when accelerating or getting on the interstate it would hesitate...now it is idling poorly and missing all the time! The service engine soon light flashes while going down the road and I took it to a local shop that scans codes free of charge and there was a communication error that prevented them from scanning the codes.

Does the ECM need replaced or "flashed" due to the dead battery and all of these issues? or am on the wrong track???

 

I'd start with a simple tune-up. Big catch, don't waste your money on aftermarket parts here. Use AC/Delco or Delphi parts on you ignition system. Spend a little more money and save yourself the headache. Everyone says they've put new wires on, if they're not AC/Delco you might as well have burned your money.
I speak from experience on this matter!!!