What have you found in your airbox??
#15
Not my Mustang, but I have a motorhome built on a Ford chassis. I was coming home from a trip, and the throttle stuck wide open going up a hill. That made for an interesting ride home. What I found was that someone before I got it changed the air filter, and tore up the old one getting it out (its in a really tight space). Anyhow, they installed the new filter with a pretty large piece of the old filter laying in the bottom of the box. It migrated down the intake tract, and lodged in the butterfly. At least it was a cheap fix!