A month or so ago this subject came up. I have an 82 turbo that does the same thing. If you turn the mixture screw up about half a turn the problem goes away but your gas mileage will also go down.
The previous postings pointed to a faulty ballast resistor (it is on the passenger side inner fender by the firewall). I tested mine per the Bentley spec and it showed that it was bad. It is supposed to have 3 wires coming off it and mine only has two. I unhooked it and the car would only fire but not run. One of the two wires (a blue one) was melted all the way back to the fuse box. Supposedly that resistor-if bad-can create the problem you have. I haven't replaced mine yet to see if the problem goes away but you might explore the option on your car.