I own a 1990 toyota pickup quad cab. 3ltr V6 Automatic. Not sure the exact Model but it has a performance emblem. Ive had it 2mos with no probs. Now everytime I stop at a light it starts to idle high low, high low, high low, then finally dies. Putting it into neutural keeps it idling evenly but once into D it chuggs untill I accerate then its perfectly fine. Its only at stops, low RPm is when it happens. Could you please explain to me WHY? And what I should do to fix it. Also, What is the Ect. Power button for?