1998 chevy venture 3.4L van has 4 DTC's

[cfrank2]

Hi, my van has the following dtc's:
P0341 - Camshaft Position Sensor A - Bank 1 CKT Range/Perf
P0401 - EGR Flow Insufficient
P0452 - EVAP Emission Control System Pres Sensor Low
P1639 - 5 Volt Referen. 2 Circuit

For the P0341 i am going to check the wiring for the sensor and most likely replace the sensor if i cant find anything worng. And for P0401 i am going to try to clean the egr valve as a new one is almost $200. But my question is, Could the P0452 and P1639 codes be related? I was thinking that maybe the wiring or the fuel tank pressure sensor is bad and it could cause both of those codes right? Where is the sensor located and how do you do it?

Thanks for any help.