90 GSX ECU issue!

Hello everyone this is my first post on galant center and am hoping for some help with a couple of my questions.
First off i am the proud owner of a 90 Galant and I am having an issue with the ecu i believe. The engine is a pretty much fresh rebuild appr. 2400 miles and basically fresh drive terrain. Along with all of this I am still having problems with my ECU! I have had one that had gone out so I had decide to do the rebuild along with the replacement of the original ECU. I had a fresh rebuild on this ECU from A1 Cardone. I am wondering if there are any issure these cars have but, I'm still confused why my car has gone through 2 ECU's but is still on original and 100% splice free wiring harness. Any help would be greatly appreciated.

Thanks
Brian