Is there a way to cancel unpaid orders made thru paypal standard after a certain amount of time?

On our site inventory is first come first serve, which causes us a bit of a problem when someone tries to checkout thru paypal standard and does not finish the payment process. The plugin creates the order and removes the items from inventory even though they have not paid for it, which we have to manually go and cancel if they dont pay within a reasonable amount of time to return the inventory. Is there an automated way to do this, say if they dont finish payment within 5 minutes cancel the order?

It would require custom programming.  A  scheduled task plugin

Check this plugin from Atluz.com it may help.

https://www.nopcommerce.com/p/1941/auto-cancel-unpaid-order-atluzcom.aspx