Car bogs at 5k rpm

[alfa164s]

Maybe you guys can help me out. Car is a 99 ek with jdm gsr. Car is running on a obd1 ecu, sticker has been scraped off so i have no idea what type it is. Car idles at 1.6k rpm with this ecu when warm and pulls hard when it wants to work. Previous owner of the car stated this ecu had been tuned for a built gsr motor. It will pull hard for a couple runs passing 8k rpms but After driving the car for some time it wont go past 5k rpm and feels like the fuel is cutting off. If i unplug the ecu and let it reset itself the car will go back to normal but then the problem will occur again. I also bought a stock obd2a jdm gsr ecu with an obd2b to obd2a jumper harness. The car idles at 2k rpm with this ecu but has significantly less power than the obd1 ecu. Havent experienced the bogging problem at 5k rpm with this ecu. Any ideas on how i can fix this problem? Do you think a simple retune can make it work properly? I am new to hondas and any help is appreciated.

[single slam 12]

Ok to me it makes no sence on the ecu thing but w/e. How about you open the ecu and see if it's even chipped and go from there. And if it is chipped and your engine requires a nice tune i wouldn't be rippin it like that you don't wanna hurt your engine..