My 90 Eldorado has a slight shake and hesitation at idle. When I am stopped at a light and then accelerate, it hesitates a second - then moves. I also feel a slight vibration- like a shaking or a miss - then the engine is fine. I don’t notice this problem at highway speeds - just at start up and from stop. I have replaced all plugs and wires, distributor, and O2 sensor. I am also running Berryman injector cleaner. Car runs better, but there is still this issue. I ran codes before replacing the O2 sensor: left and right fuel difference. The code is now cleared after installing the sensor. No codes now. Any ideas on what to do next? Thanks!