This sounds like a great time to give your throttle linkage a thorough inspection.
It may help to have an assistant work the pedal while you watch what is happening under the hood.

You might find:
a kinked, rusted, or frayed cable.
the pulley at the engine end of the cable has unusual wear.
a bracket holding one of the parts has been bent & misaligned.
a stray bitof carpet interferes withthe pedal itself

If you disconnect the cable and operate each part seperatly, it should be easy to identify which part of the mechanism is binding.