My car (86 420SEL with 90,000 miles and FULL maintenance records) idles roughly and hesitates to pick up under low throttle. About mid throttle just off the line the power jumps in and gets the car moving. The shaking is most drastic at low or high temperatures, but around 75 degrees it is most subdued. Injector cleaner seems to help, but it is so subtle that it could be my imagination. I have replaced the the plug wires, and I am wondering if injectors are next. Or am I on the wrong track. Thanks for the help.

Nick