A while ago my car was doing this and it stopped. It will skip when cruising at 60 and the rpm will fluctuate rapidly. When I am at a light with brakes on it acts like it want to push me forward. When I put gas like 1/2 down it bogs and all of the sudden the car acts like it try to catch up and drive normal. I have replaces IAC, Igniter, Crank shaft sensor, Air intake, Just did water pump/ timing, spark plugs and wires. Need some help not sure what to look at next. Thanks