I bought a new used 1999 and it was doing that. The Dealer replace the overdrive solenoid. That never solved the problem. My light only starts to blink when I really put my foot in it say 90+mph. It then resets when I turn off the engine and restart. It probably has to do with a pressure sensor in the auto trans. I now have put over 70,000 mile for over 115,000 miles and have not had a problem so I let it blink when it comes on. Try having the filter replaced/cleaned too.