Similar to Dave's comment, I fought and fought and fought with the idle on my sniper until I replaced the throttle cable and all of those issues just went away.
I was thinking your post was mainly about the secondaries, but it sounds like you are having similar idle problems.
As a test, unhook the throttle cable and rev it up by hand, then just let go. If it still doesn't go to zero TPS, then you have a problem in the sniper. If that does fix it, try re-routing/replacing the throttle cable.
