sorry to hear about your headaches;

first question is, is that car running standard boost?

misfires could be a whole host of things and sometimes a pain to rectify

common issues which wont cost alot:

phase sensor; sits inside the dizzy cap and the wires corrode to it - check this

change the fuel filter

check the voltage at the fuel pump; you MUST rewire the fuel pump for a direct feed from the battery.

check those first and let me know