start with the basics, check for vacuum leaks, coil output, etc. also when you advanced the timing, did you disconnect the spout connector? if not then you dont really have 20 initial timing as the computer is correcting it to factory specs.
if these check out, then start looking for something like a bad cam lobe, pull the codes from the computer and do the tests indicated by the shop manual. also check ALL your electrical connections for cleanliness and proper connection. remember to use the dielectric silicon recommended by ford on the connectors after you clean them.
clean the throttle body and the injectors. check the plug wires for proper resistance. make sure your valves are not adjusted too tightly.
my mind is aglow with whirling transient nodes of thought careening through a cosmic vapor of invention.