On most VW of that era, I've got a 82 Rabbit conv, there is a cold start device that allows additional air to enter the intake so that the fuel system goes rich. Sounds as if the device, mine is called a "Cold Start Valve" (clever those German to English trnaslators). Yours could be stuck open and not closing the additional air inlet when the engine reaches operating temperature. Alternately, they could have used a device that adds fuel when the engine is cold and it could be stuck open. My guess is on the air valve.

Also, on the 82 they had a fifth injector in the intake to really add fuel when the engine is cold, don't use that much in NC! That could be stucdk open or leaking. That is easy to check.

The cold start air valve on mine is a bypass around the throttle body, it is operated by engine heat and an internal heater.

I don't know how the 89 works, but all fuel inj. Bosh stuff has to have a device like this.

Happy hunting.

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GeneN
Charlotte, NC
1994 C280 135K