2002 Saturn Vue: Warning lights on dash erratically go on & off

I recently had my vue overheat and spew coolant out beside water pump. Next night, I refilled car with coolant and it quit overheating. I thought I had a leak. On my drive to mechanic next day the temp was perfect. However, the "service" light, "ABS" light, & "Brake" light would randomly flash on and off. Also, my tac would randomly go dead for a split second and start working again. My mechanic confirmed water pump had a leak and wouldnt hold pressure. He changed water pump & timing belt and it works great. However, those 3 lights + tac continue to act up. On a rare occaision, the "service engine soon" light will flash on and off. this all started after the car overheated. Someone told me that sometimes the steam from the engine overheating will throw some of the sensors off. Anyone ever had this problem? Any help would be appreciated.