Jeep stalling - identify this part...pls

Hi, this post is for a buddy of mine. ( i have grand cherokees... )

01 xj, 3inch lift, 31's. everything else is stock. His rig started stalling, so i checked the obvious, crank sensor, coil, distrib, computer...everythings fine. the one day we were driving and i was hearing a ticking, i popped the hood and traced the noise back to this little valve on the passenger side of the firewall. I cant post pics cause im at work..but i can tell you theres a green capped shrader valve that goes to it with 2 lines (fuel vapor??) and a electrical connection. if you google cherokee engine pics , a white 99 comes up (jpmagazine) you can see the green cap and the part im talking about....


can someone please identify the part

thanks

canister purge valve/solenoid-- it's normal for it to cycle open/closed and click.