[autojack]

I'm dealing with this in my 88 right now. I had the same lurches as you, then the car died. I got it to run briefly several times but not long enough to drive it. Eventually it wouldn't start at all. In my case it wasn't the relay. I've confirmed I have spark (after something of a wild goose chase) and now I'm preparing to test the fuel pump. Follow along at http://forums.pelicanparts.com/porsche-911-technical-forum/916075-broken-down-near-pt-reyes-ca.html