My celica won't stop !! Help me pleaseeee.

Hi I'm new to the forum , I have had my celica VVTL-I for 2 years and never had a problem UNTILL a couple months ago I put my foot down ! It's a twin cam as you already know and when I got to 6.5k rpm it kicked in and didn't want to stop untill I switched ignition off and rolled to a stop, I gathered It was the throttle body so I cleaned it and it happend again a week ago, but this time I checked the throttle body and spring mech was closed , all ok , re started car and it rev'd the hell out of it , stopped car and waited for 10 mins and all is ok ? Is this a known electrical or a mechanical fault in the system , please help, regards Mk