It sounds as if the fluid level is still in question. These transmissions are very finicky about this. It needs to be checked after the fluid is fully warmed up, on level ground, while running in park. If the fluid is cold, you will have erratic readings. Only fill to the lowest mark.

Also, since this is intermittent, check the kickdown switch behind the accelerator pedal. I had a problem on mine where carpet fibers were getting in the way and causing the switch to stick.

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Sam

84 300SD 350K+ miles ( Blue Belle )