i need a ECU memory# ? for my 323

i drove to central america and ive been having some serious fuel usage problems with my 1988, mazda 323 1.6 f.i. after i took it to a mechanic.

with a new mechanic after checking everything i am told that the ECU in my car is for a newer model 323(which it could have been switched out by the previous mechanic?)

im trying to find out what the correct memory# is for my car. I beleive the memory number is the reference number i need for the ecu?

the vin# on my car is JM1BF2329JO153543

any help you can give me getting the right number

thanks alot jhonsmazda