Please help, we have tried EVERYTHING and are already $1000 deep in parts replaced.

I recently purchased a 2007 Silverado 1500 Crew 5.3L

Upon getting home the check engine light came on. Code was P0335 (Crankshaft Position Sensor A Circuit) along with it came the notification for stabilitrak which would also cause rough shifting at low gears and the engine to stall occasionally at idle. Reset the battery/codes and truck runs fine zero issues till code comes back on.

We replaced:
-Crankshaft sensor and connector wire
-Camshaft sensor
-Timing chain (tensioner, sprocket, etc)
-Spark plugs and wires
-Fuel pump (had low pressure and would decrease over time)

After this everything ran fine no codes no issues. Took it off the lift and for a test drive and the check engine light is back on and so is StabiliTrak message.
Ran the codes and came up as P0335 (Crankshaft Position Sensor A Circuit) and P0455 (Evap Emissions System large leak detected)

I am at my wits ends and my pockets are about empty... I don't know what else we could possibly replace. Please help.