I have a 2004 Marda 6, 3.0L, 5 speed manual tranny, with over 240k on it. Bought vehicle from an auction several months ago and wasn't running. Didn't know anything about it other than it didn't start. Really the only thing I had to put into getting it to run was a ecm and reprogram the key. Fired right up no hesitation no cel. The car runs and drives great. However there is a P0340 code that always returns when I try to clear it. What could it be, I'm thinking the time may be slightly off, but no cel is on. Changed both cam sensors, still same issue.
The car also shows no rpms until above 2k rpms. The cruise control works but will surge and disengage by itself within 10-20 seconds. May be a vacuum leak. Any advice.