Ok for starters I bought my car mid Nov. of last year it has roughly 113000 miles on it and the only mods on it are a cai, bbk 78mm throttle body, shorty headers, and catless exhaust. Until this past weekend I've had no problems with it but Saturday it started running almost like it had a miss. Then the CEI came on so I went down to autozone and it showed P0171. I also noticed a slight ticking from under the front seats. Could a blown collector gasket cause the 02 sensor to misread?