Is this logical?
For the past year I have been fighting with a crankshaft error, P0315 variation not learned. The 4.6 LH2 Northstar learns it and will keep it for a day maybe a month but then the same code comes back.
In the year the computer has been replaced twice, the MAS has been replaced twice, the throttle body has been replaced, the crankshaft sensor has been replace, electrical connections have been replaced to the MAS and the crankshaft sensor. Two other sections on wires have been spliced and replaced.
The same error code keeps coming back. The downside of this code is randomly but often the engine starts but goes immediately into limp mode. This symptom has progressively gotten more frequent and seems directly related to cold weather. If I place a jet heater directed under the engine I can get it to start and not be in limp mode, still have the error code. Otherwise the crankshaft position has to be relearned.

So, being thousands of dollars into this I am at the point of purchasing a used engine and putting it in. I figure there will be some problems with a used engine but if they are different problems (anything other the crankshaft position not learned) I can deal with that. I haven't been able to drive my car further then 10 miles from home and I have to make sure the temp is over 35 degrees to even attempt that. I am really disappointed and willing to try anything.

Thoughts?