Ford Repair: runaway throttle, full throtle, accelerator cable

Question
95 5.8 econoline , 180,000.  accelerates to full throtle for no apparent reason while driving. Very dangerous. it happened 3 times after engines heats to op. level. MUST WAIT UNTIL ENGINE COOLS BEFORE IT WILL IDLE AGAIN. Butterflies remain closed while engine runs out of control.
DAMN SCARRY! Went shopping for new van today, but I cant sell this one as is, and it's to dangerous to give away.
ever heard of this???

HELP PLEASE IF YOU CAN

Answer
if it does frequently have someone scan it and see what temp reading is when this happens if ect sensor shows hot (this is for ecm not guage)
the ecm will raise rpm to try and cool it down-make sure coolant is full please check cold only-nothing around accelerator cable and floormat is not riding up and getting caught under bottom of pedal
please don't laugh about the last one it happens every year i swear
good luck.