i bought an 87 non turbo auto car thats had this shifting problems ever since i got it. when you put it in "D" it will be in 3rd gear and wont downshift to 1st or 2nd on its own. if i drop it down to "L" it will go into first gear. in position "2" it will be in third gear. the overdrive on/off switch works and controls o/d. any ideas on where to start? i am getting tranny codes because the o/d off light is flashing, but when i jumper T and E1 it wont tell me what code.