My W126 has become difficult to start. Unless I depress the accelerator pedal the engine just dies. The only way I can get it start is to keep the accelerator depressed until the water temperature is almost 80 degrees - then I can take my foot of the pedal and all is OK. When I have been out on the road the engine did die when I was in a queue of traffic, although it did restart after a couple of turns of the ignition switch. Also, when it is ticking over, the engine revs rise and fall occasionally. My neighbour says that I should change the fuel filter (I have never changed it in the 9 years that I have had the car) - would this improve matters? What do any members think might be the problem?