Hell-o Roc-A-Bac here,
You can purchase Ford Code Reader for years 1981 to 1995 about $40.00 at most auto parts stores.
I too was having a check engine light intermitting, had it checked, mechanic said no codes were registered.
But still the light would come on, so I put some fuel treatment in my fuel and ran a higher grade fuel for a
tanks worth. The light never came back on, but my '94 2.3L XLT started not restarting after running fine, had
it towed home, tried it when it was delivered and unloaded, it cranked this would happen two additional times (less the towing). So I bought the Code Reader and found their are two types of codes the computer holds in memory one activates the light and the other doesn't after it has been committed to memory. One was related to the secondary curcuit of the fuel pump (the fuel relay) the fuel relay was intermitting so I pulled it out and checked for a short, no short sometimes all you need too do with plug in relays is to clean the contact prongs and reinsert as in my case, but that didn't keep me from buying a new spare for the road.
If you should purchase the OBD-1 Code Reader read the Retreving Codes proceadure section all the way through several times to save yourself time. Good Day