I have an 1987 Porsche 924S that is running very poorly. I have replaced the following: spark plugs, plug wires, distributor cap, rotor, coil pack, idle stabilizer valve, fuel injection temp sender, and all the vacuum lines. The problem with the car is: When the engine is cold it runs very poorly after about 15 minutes the car starts to run better, but when you rev the motor up is sounds rough through about 3500 RPM s. If anybody has any suggestions I'm very open for help.
Thanks,
Sergio

 

I would look at your ignition control module in the drivers side headlight area (behind the bucket, attached to the front wheel well)