I changed the valve cover gasket on my girlfriends Lancer Oz because it had failed totally and leaked oil all over everything causing the belts to slip and squeal. I rinsed down the motor to get all the oil off and now the transmission feels like its slipping. If you pin the throttle down it revs up to 5-6k and hardly moves. I cant get it somewhere to scan the codes and I dont even know if it has any because her engine light has been on for the last 2 years and she didnt care. I know nothing of these transmissions but Im wonderind if there is a sensor I got wet or something else im not seeing

Any ideas would be greatly appreciated
Thanks