Getting error code 12 on the diagnostic which points to the ECU / starter / distributor circuit. Not touched any of the above while I did the water pump, only to take the alternator on and off. Checked the connectors for that, bone dry and no splits in the wiring. Car idles rough at around 300/400 missing like a mother fecker and blip of the throttle, lift off and it dies. Starts right back up again but miss and rough idle is there. When cold it did start up and idle as normal for about 40 seconds then started to miss and idle rough. I've checked the dizzy cap, leads, plugs and all the connectors and everything seems well. Any ideas where to check next next?