There is no aftermarket PLUG AND PLAY solution. I have a 95, and it very much does not have a stock ECU. In fact, I threw the stocker in the garbage and have been running completely off Megasquirt for over a year. Best mod ever done, hands down.

95 Eclipse GS: 10.5:1, Crower 2's and MSII
186 WHP - 150 WTQ
14.697 @ 93.85 MPH......Gone, but not forgotten
99 420A Avenger: Given to my sister
99 GS OZ: Sold
03 Evo 8: Family Car with balls