UK Car Repair: Daewoo Leganza 1998 2Ltr, daewoo leganza, short periods

Question
My speedomiter drops out internitently for short periods and then returns to normal. Whilst the speedo is not working the car will not idel and stalls when the reves are allowed to drop. When the speedo returns to normal the stalling stop's.

Answer
I'm not sure if the speedo is the cause or the result.  First I would check the connections to the speedo drive near the transmission, it sounds like a loose connection but it may be inside the ECU.  These faults are sometimes difficult to trace even with the car. So you will have to take it to a mechanic.