1998 Cadillac Seville ENGINE TROUBLE

98 seville sts. Well I bought the car about a month ago and its been nothing but trouble. It normally takes two or three times to start but would run fairly and it idles ruff it goes up and down. I took it to advanced to get the codes and it lead me to replace the o2 and crankshaft sensors, and the ignition moduel with new coil packs. It still has four codes 2 of each P1350(ignition controll system) and P1375(IC 24x reference circut high voltage). Im really tired of buying parts that it dont need to anyone with and wisdom for me would be greatly appreciated!