Here are some valuable pieces of information which helped me to learn a lot about my Ford vehicle electronic brain. 

eectch98.zip Technical notes on EEC IV MCU (80 pages PDF document) 
eec-info.zip Miscellaneous EEC IV info (diagnostic codes, wiring, etc)
eecsk111.zip EECSucka - a ROM dumper for the EEC-IV (schematics, DOS executable)
asm8061_100.zip Intel 8061 assembler (Win32 executable and C source code)
dis8061_115.zip Intel 8061 disassembler (Win32 executable and C source code, plus A9L ROM image layout)
a9l_dump.zip Classic A9L ROM image (Mustang 89-93, E9ZF-12A650-AA)
eeccalib.zip Calibration info (A9L, J4J1,  U4P0,  X3Z)
deec02a.zip EEC IV simulator -- runs ROM images on a PC ;)

The EEC IV Bible by Charles O. Probst:

This is how these beasts typically look like: