I know , I'm posting , way after the fact.
But a problem I found may have some bearing , throttle pedal hinge was rusted, from shampooing carpet. Cleaning and lubing the hinge cured my problem.
This may not be any help, depending on the injector pump you have , but the Dodge ISB's with the inline mechanical pump 1994 to 98. Had a campaign to replace throttle return springs, weak or binding springs due to rust could be an issue. The Cummins parts would not be cheap, but not as much as a pump o'haul.