1986 timing full advance at idle, then retards as accelerate

[CarbedNotch]

My bronco has the problem where at idle the timing is at almost 40 degrees. Then when I give it gas, the timing retards!!!
It is at 15 degrees initial timing but when I plug the timing advance plug in, the timing jumps to maximum advance! 35+ degrees. The truck runs badly in the midrange and its obvious something isent right... What can I do to reverse the timing curve on the distributor please?