New TB Issues..
draw-to-open length, only the later F-body ones have
a profile that opens more leisurely down low and faster
toward the WOT end.
Yes, you can swap the throttle shafts. But I think this
is not where your problem lies (unless this is a non-stock
casting).
If the blade still won't close with it off the car, then
check the stop-screw which is on the underside of the
idle stop boss. Allen screw if I recall.
If it's only a problem on the intake then check the cable
adjusters (multiple, on my car) again, maybe bend the
cable bracket?

