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lockup o/d cruise problem

  1. Getting a php Chip But have lockup problem *advice please*

    99-03 7.3L General Discussion
    i just bought a 99 f250 auto 7.3 about 2 months ago and should be getting my php pheonix chip today but noticed my torque converter will go in and out of lock up around 40mph. If i speed up it will go away but only when im cruising around that speed. The overdrive light worked fine but when I...