Sounds like a bad MAP sensor located on the passenger side rear on the evap case. Also check the hose that goes from the MAP sensor to the intake and make sure the port in the intake is not plugged.
I hope my assistance helped you and resolved your concern, if you need further assistance please ask.
Please note, your Deposit doesn't constitute a payment. Please click the 'ACCEPT' button to allow me to receive credit for my work. Positive feedback and Bonuses are appreciated. Thank you, Shawn.