On my 72 280SEL 4.5 there was an idle air screw at the front of the air horn. Turning it out allowed more air thereby raising the idle. Is it too low? The TPS, "throttle position sensor" is under the large black plastic cover screwed onto the throttle body side. A multi wire connector plugs into it. Gently remove the cover and you will see a series of copper lines and "fingers" that brush across them. Clean the copper lines with a pencil eraser and see if its better. Also from memory, I believe you can rotate that switch ever so slightly to anticipate changing the injector pulse width. Without the book, I dont remember the resistance spec? I would think you could mark a point of reference on the cover by the screws and move it and see if it improves, and if worse go back to original setting. My car never hesitated, in fact it was hard to leave a stop light in the rain. The rear tires would break loose! at part throttle. Another adjustment is the manifold sensor on the left inner fender(driver side) at the opposite end of the vacuum hose connection, there is a set screw to move the diaphram within it. Sometimes this screw is covered with a type of wax or a metal cover. Moving this screw ever so slightly will alter driveability. Again mark it prior to turning. Cannt remember which way? And finally there is a serrated knob on the ECU as well to adjust mixture. Best done hooked up to an old school emission or smog machine. Hope this helps. Sold my car 10 years ago!

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.