Originally Posted by Reptile
...Start by checking the state of battery connections, distributor and refreshing your grounds (this is a big deal). After that there are so many possible causes and you might be shooting in the dark: O2 sensor, coolant temp sensor, plugs to name a few.
Super big deal is the braided cable where it connects to the firewall. This must be removed, the paint scraped off the firewall, and the cable end polished up nicely, and then reattached securely. Check the cleanliness of the cable at the back of the head also.