2002 Montana Engine swap now have 2 codes

Been referring to this site for a long time for advice, 1st time poster however. Bought an 02 montana with a bad motor and just got it replaced and running. It's throwing two codes, p0102 for low voltage at maf, and p0443 for evap solenoid circuit. I'm also noticing that the idle is purging up and down constantly. When I drive it's fine but just at idle it's constantly up and down. I'm wondering if it's possible I may have knicked something on a wiring harness. Both of these codes are for something running off the same leg of the wiring harness. Any help is appreciated