the car runs good for about 20 minutes then starts bogging and then dies(CEL is on). RPMS starts going crazy jumping up and down. Sometimes the car starts right up, sometimes it wont. CEL gave crankshaft position senor code, changed it ran good for a day and it went back to bogging(as if it were choking) then dies. A known mechanic said it could probably be the Cat, ordered one from zzp and still same issue. Any help pls.