I assume you have tried to lube the throttle cable, spray some lube down the cable from engine end.
A loose/disconnected ground strap(drivers side head to firewall) will cause throttle cable to become a cab/engine Ground this dries out the lube in the cable.
Check that the spring on the throttle linkage isn't broken, it is circular, like a clock spring, you can add an external spring for now, throttle must have a spring to pull it closed against air flow/pressure.
If you have cruise control disconnect that cable from throttle linkage for now, see if problem goes away.
See if you can reproduce the stuck throttle with engine off, i.e. open throttle manually and slide it back and forth to see if a bushing is worn out causing it to stick.
Also have some one push gas pedal to open throttle, if it only sticks when using gas pedal then cable is the issue, broken strand in the cable is sticking, same can happen on speedo cable causing needle to jump around.
Opposite the throttle cable side on the throttle plate shaft is the TPS(throttle position sensor) it could be worn and causing throttle to stick.
If you can reproduce stuck throttle loosen TPS and if throttle releases replace TPS
Last edited by RonD; 01-23-2016 at 11:03 AM.