I know this is an old post but also look for a misfire. while E-27 is a crankshaft position sensor code, it is often caused by a misfire from things like a bad coil, spark plug, tight valve, etc. It could be in the crank position sensor circuit but the misfire is a more common cause.

Crank Position sensor.

How does the truck run?
If it won't start or goes into " limp home Mode" look at the sensor. if it runs poorly but you can rev up the RPMs check the plugs and coil packs.