ToothedAnchorNut molded\imbedded in side of Plastic ThrottleBody,
bolt stuck possibly due to being OverTight, WrongSize, CrossedThreaded, Corrosion...
I'd first try
~ spray it with PentratingOil
~ gentle tap bolt 2 or 3 times
~ let that soak for an hour
~ again PenetratingOil
~ again gently tap bolt
~ wipe up oil excess
~ try ViseGrips; LeftyLucy, RightyTighty
If that don't work
may need to drill the bolt with slightly smaller bit.
Then clean up the AnchorNut with a ThreadTap.
Use AntiSieze or a little Vaseline when you put it back together
& don't put the MuscleMan on these plastic parts.
Hope this helps.
Most likely someone has been in there b4 and crossthreaded the screw into the nut. At this point the nut is fubar and it is doubtful you will get the screw out.ok and now the screw broke off while twist it out and now its barely enough to grip with vise grips
so ive got to find some kind of extractor or some sort to get the rest out