Couple things - take apart, clean and lube all of the pivot points on the linkage. The one on the IP is a pain to get to but it can be done. Don't skip that one. Next start breaking it down to try to determine where the sticking is. You may want to start behind the gas pedal. Look at EVERYTHING between the pedal and the IP. You should be able to find the problem - something is hanging up/binding.

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Jim