Just bought my first Cadillac a 1993 Seville sts with 65,000 miles. The car sat for 2 years. I ran through dry gas and Techron fuel system cleaner. Sometimes car runs perfectly smooth as glass and other times real rough idle with the tach varying from 1500 to 3000 rpms. Checked codes only 1 active code and some in history. It's a beautiful car in near showroom condition. Codes as follows:
Po23 h
Po52 h
Po53 h
Po57 C
Po91 h
P109 h
Po95 h
No sir acp
S016 h
S044 h
S055 h
S061 h
S062 h

Local mechanics just recommend let's try this and that I'm looking to fix the problem not a parts changer. I've only had the car for about 2 weeks and really want to get this car going. This is my first Cadillac and don't know anything about these cars. Any help or insight would be appreciated. Btw when it idles rough it drives rough for like a minute and usually stalls and rough start. Other times starts up and runs beautiful ..... Please help