The pierberg autochokes tend to stick on, giving you an incredibly rich mixture. My old golf driver used to have a pierberg 2E2 carb, which when you looked at the gases on a crypton tuning monitor, it used to flood at high revs. (it should use less fuel at around motorway cruising revs) It would give terrible fuel economy and throw a lot of smoke out of the back.
I'd replace it with a Weber direct replacement. It'll have a manual choke but it will make a huge difference to the car's behaviour.
