I have been getting this code off and on a lot an also checked all lines an tested purge valve an found no problems.
At times though as I release the fuel cap a rush of air comes out .
I've replaced gas cap2 times also.
It's this air noise normal?
Sometimes a faint gas smell is noticed back near tank also.
Any ideas what to check?

 

Having a gas smell near the tank sounds like possibly the vapor/charcoal canister leaking. Look along the drivers side undercarriage, and check for cracks/leaky vacuum lines. I don't have personal experience on a dakota, but I've dealt with one on a Nissan Sentra, it was under the trunk on the nissan, almost in the bumper.

 

As in the black box itself?
Lines been replaced..maybe loose charcoal in it ..ill recheck it..
How do I test the purge valve?
Is that not opening maybe?

 

This is gonna soind crazy but true..

I took off has cap when fuel level low an `~~~swish~ a large heap of air released from tank!

​​I filled the tank 3/4 tightened cap an clicked 3 times to close...Reset computer.
I have now gone over 300 miles now with NO CODES.!an added more gas one time with 3 clicks./close! STILL no codes, not even pending!

What gives?!
Does low fuel signal a code or is this 3rd gas cap disfuctioning ..
Seems once that strong air come out an I kept plenty of fuel in it it doesn't set code.