Check the purge valve . Remove it and put 8 volts to it , it should click on and off There is a check you can do on the purge system,.But i dont know it off hand ..

Purge valve port is so small it won't make noticeable affect even if it is wide open or plugged closed. The port in the throttle body is apparently above the throttle blade at idle, cause it pulls no vacuum at all at idle, then begins to pull a small amount as engine is revved a bit. my solenoid stuck open years ago, and I haven't bothered to replace it. So, probably not your problem.
Of course, if the purge is plugged up, you're gonna have possible problems with the cannister and fuel tank. Just to eliminate it, pull the line from the left fender purge solenoid to the throttle body, put a finger over it at idle and at 1500 and see What happens:
- idle, no vacuum on the removed line, no click from the solenoid on the fender
- 1500, a small amount of vacuum, and the solenoid will click if the engine is warmed up.

Best way to begin trouble-shoot for fuel is to check the EHA duty cycle, and see if the system adding or pulling fuel out (rich/lean).
All you need is a digital volt meter with a duty cycle capability and a bit of reading herein to see how it works.

DG