From EX Auto sparks with Bosch....retired now 78.... all i can say is when you had the emisions done was it noted there was "Fluctuations" in readings when Hot as a leaking injector would give your fault...normal they clear for a while only to come back again...even the 5th cold start injector can give this trouble...if you can get the car to a help-full garage and see what the "Co "is when the idle is bad...normal "Co " is 1.3 / 1.5...if its a fuel problem it will be proberly closer to the MOT limit on these cars 3.5...you have changed the "Yellow Temp Sensor"...thats good...if the "Presure actuator" was faulty then this would also certainly give this Fault....but not give Fluctuations in Idle...but way way High emisions, so i come back to a "Co " check when Hot and giving the trouble, should you want to know how to "Test all 4 injectors".....plus the 5th cold start injector for leaks, ive wrote before hear, but will write again. i can say slight Leaks affect Idle only on these cars....power / performance good. Presure actuator fault....performance poor.....very very smoky / stinky on exhaust.... best i can say. hope of help. Peter