96 polo idle problem

Any help to stop me going insane would be most welcome.The problem relates to my 1996 1600 Polo.It started off idling errattically and a fault was diagnosed with the Throttle Body and this was replaced and fault codes cleared and reset.As soon as the engine reached normal temperature the problem resurfaced.The Temperature Sensor and Spark Plugs have been replaced and eliminated and all the Electrics,etc have been checked with a Bosch KTS diagnostics.All vacum pipes and the MAP sensor and the Intake Manifold have been replaced as a precaution.The ECU is reading 0 Faults and has been reset 3 more times with no change in the idling.The engine runs perfect other than this idling fault and until it warms up there is no sign of a problem.At the moment everyone that has attempted to rectify this fault has given up,including a Bosch approved technician.I myself have checked just about everthing there is and can think of nothing else other than the ECU,but several people,including an ECU supplier are of the opinion that this is not an ECU fault.Any help would be most appreciated. Evil or Very Mad