We had similar trouble a year ago, except that the cable on our '92 Land Yacht (with a Chevrolet 454 engine) broke, and we had no acceleration at all--on a Jan. Sunday near a small town in northeast MO. We managed to idle into a grocery store parking lot, dumped our water tank to avoid freezing problems and after several hours were rescued by generous and good men who got us to their adjacent places of business, gave us an electric hookup, removed the broken cable, and promised to work on getting and installing a replacement the first thing in the morning.
Unfortunately, the part was not immediately available, so these enterprising men managed to repair the broken one and installed it, so we could be on our way. They also provided us with the part number. We subsequently ordered the part and have carried it with us ever since so that should the repaired one break, all we have to do is find a mechanic to install the new one.
I guess my only reason for writing is to encourage you not to give up on finding a replacement part unless you have exhausted all avenues.