My 260E has recently started displaying an idling problem when first started. It starts easily, idles a few seconds at 500-700 rpm,then races to 2000 rpm,then back to 500.It repeats this for four or five cycles, then settles down to normal(5-6 hundred rpm). A local shop charged $75 for diagnosis-consisting as far as I could determine of removing the air filter and breathing on the under side-then they quoted a charge of $850 to fix it by replacing the 'throttle position sensor'. Is this a reasonable diagnosis and estimate?
Where can I get a good repair manual for the '87 260E?

Harry - I'd use the SEARCH facility here before shelling out any money. There's been more than one mention here about problems similar to yours.

You can test the TPS sensor yourself. Mine was doing the same thing as you described. I took an ohm meter and measured for continuity at the tps connector. It is a three pin connector and should have continuity with the engine at idle at two of the connectors, and have continuity at WOT on the other one of the two. This connector is right by the bottom of the air cleaner at the front of the engine. It is quite expensive as it comes with the throttle body. I removed mine and took it apart and cleaned it. Works like a charm. :)

Steve, good advice but you should also look for a smooth transistion from low resistance to high resistance. Especially look for a jumpy reading as the throttle is slowly opened or closed. If the TPS is dirty, you could get intermitant readings at any position.