1999 ford E-350 van revs and lurches forward while in drive with my foot on the brake?

This van has an automatic trans and the 5.4 cng motor the abs and brake light are on but they have been on for a long time and this problem just started recently the problem happens anytime the car is idling whether its in park or drive but it idles fine for about a min but if it sits any longer it starts to rev any thoughts on what my cause tis would be very appreciated im a noob to this yahoo answers thing so hopefully i gave enough info