5S-FE MK2 Non-Turbo Engine Wont rev....

5S-FE MK2 Non-Turbo Engine, 4.5k, drives, idles, past, camry, spare, weeks, found, issues, 5sfe, changing, issue, lying, fixed, bought

93 5sfe. Had some issues a few weeks ago and found changing the ECU with one I had lying around fixed the issue. The spare ecu came with the car when I bought and while it idles and drives ok it will not rev past 4.5k. Would having an ecu from say a camry be the cause and I need a MR2 ecu?