help! ECU problem!

have an 89' honda CRX HF with a b18A1 swap.......Car has been running great even quicker then it probably should be but I went to get safety and emissions done on the car and they said the car is running to rich? its burning to much fuel......I dont know much about cars my cousin is taking car of everything and he said that when the swap was done he thinks either the wrong ECU was switched into the car OR the ECU is just bad.....any suggestions? what ECU should be in the car and if it does need to be replaced what ECU needs to go in it and where can i get it? If anyone can help at all it would be greatly appreciated since im paying for a car I cant get registered right now.....

well first of all if your car is running rich it could be a number of things, for example you might want to check your distributer to see if it is advanced, cause that could cause you to run rich. also if you do need a new ecu you need to get one out of a teg LS