I have heard of the Eclipse having ECU problems but I would nor replace it without being certain it has been tested and fails. With the engine running hit the ECU with your hand several times the engine should not stall if it does the ECU IS bad! There are several companies that can inspect/test/repair the ECU. I like Fuel Injection Corporation in Livermore CA, I have also used http://www.siaelec.com/ (they may only do American cars but I have had good luck with both these companies (bad luck with some others).
There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online