We continue to have problems with our '83 DMC. We have gone through the entire injection system, cleaning the fuel tank, replacing the fuel pump, filter, accumulator, and injector rubber seals. We have also replaced the oxygen sensor. Originally the distributor plunger was jammed but we freed this using injector cleaner and compressed air. All the injectors are spraying with a normal spray pattern. We have checked the fuel pressure, control pressure, and rest pressure, and all are normal. The car will not idle happily and hunts. The contol pressure regulator is clean and the frequency valve buzzes during warm up. The compression is consistent in all 6 cylinders within 10 psi. We have tried adjusting the mixture but it will only run rich and the gas consumption is very poor {about 18mpg on highway}. We have changed the plugs and set the timing to 13 degrees BTDC as specified. The engine revs up fine and smoothly when the car is stationary. Under load, it accelerates in spurts and then hesitates. When decelerating it jerks and hunts. We cannot detect any vacuum leaks.Can you give us any suggestions? Thanks, John 16727