Chris, I had an issue with this and my Perfect Pass after a couple years, it used to back off so much that PerfectPass wouldn't have enough throttle to speed up and would eventually give up.
You can buy special "throttle brakes" or some such thing, but much cheaper and easier to get are some simple cable clamps that will do exactly the same thing.
These are small U-shaped bolts with a couple nuts on the end that you can buy at most any hardware store and they cost less than $1.
You place them right on the outside of the cable jacket near the throttle lever and just snug them up a bit to provide a little friction between the jacket and the cable that runs inside.
I used two of them spaced about 2 inches apart and tightened them until just lightly snug. This created *just* enough friction to hold the throttle in place without changing the feel. Think *small* adjustments until you find the sweet spot.
My throttle alone works nearly like a poor mans PerfectPass by itself and holds speed really easily. With the PerfectPass on...well...its Perfect again since I added the cable clamps.
Special thanks btw to PerfectPass for solving this for me, turns out it was just my throttle cable wearing in a bit and loosening up. They got me a solution within 3-4 days and its been holding great for 3 years now.
Edit: Some throttle assemblies have a friction control built in...mine didn't so that's where the cable clamps come in.
(Message edited by big_poppa_pump on June 21, 2007)