I have a 98 Mazda 626 V-6 with 111,000 miles. I just changed the valve cover gaskets, replaced fuel filter,changed plugs,O2 sensor,cleaned EGR valve and throttle body and replaced gaskets on both. Before all the work the transmisson worked fine. As soon as I got the car back together and drive less than 1/4 mile the OD light started flashing and transmisson shifted hard.I can help but think there is something I have left unplugged as there were many hoses and connections that needed to be unhooked in order to remove the intake manifold. I have looked and can not see any thing left unhooked.I hate to take the car to the dealer for something I have over looked. Please help.

 

The only thing that comes to my mind at the moment is cable from throttle body to transmission. Maybe it needs to be adjusted?