unknown prob.

i was not able to get car in shop today and i have no garage. so tomorrow is the day. my problem is i get a check engine light and my car seems to be less powerful as in maybe in safe mode. i need a oil change im 500 over do to a trip. i get a shakey feeling from the engine like a choke or a cough. i just had my exuast replaced and cats removed. the third o2 sensor is in a h pipe. when i got three days after exhuast is done my first ce light my car ran fine. i was thinking o2 sensor so i un hooked the battery and ce goes away. two more days later driving with cruise on i get another ce. i get a slight hiss from engine and notice a little bit of an antifreeze spatter. car is now running very poor. can a waterpump going out set ce lights? it could be a leak in the radator. im getting in the garage to determine and do an oil change tomorrow and check codes. any bets o2, oil, pump, or all the above. how does a car react before water pump lock up?