99 G3500 Van 5.7l -- Check Engine Code

Hi all,

Patient is a 1999 Chev G3500 with 5.7 engine. Recently new parts include Fuel Pump, Fuel Filter, Dist Cap, Rotor, Plug Wires and Plugs...Always well mantained with 79k on the clock....

For a while now it has run a little rough at low to medium speed, seems to be aggravated when it is wet outside... other times it runs just great....

Now I am getting the SES light and my Scanner reads a P1345 code...My book describes as Crankshaft Position/Camshaft Position Correlation ??

Truck still goes, but runs even rougher at times, but not always....

I could really use a clue as to where to go from here....

Thanks

Jeff