Will not idle down when shifting.

Check throttle and idle cables are lubed and move freely also check the throttle lock is not binding with the grip. Could also be IAC is sticking or needs replaceing

Make sure the throttle stop(the little star wheel under the right handlebar control) isn't tightened against the throttle. Also lube both the throttle and idle cables. If problem persists, either the cable is pinched near the steering head, or the cable is frayed inside and needs to be replaced. Good luck!

try this remove the throttle cable from the throttle body and re-ve the engine with the just the linkage on the side of the throttle body if the engine responds like it should replace the throttle cable if the throttle still sticks then replace the throttle body......good luck

let me know how it come out.

you will have to have a nulti meter and unplug the sensor and che the ohms on the sensor when you move the control, it should move up and down on the ohm numbers smoothly if jumps as you apply throttle then you have a bad sensor

they can stick in a number of places.
You may need to dissassemble the hand throttle assembly
Make sure the plastic twist grip turns freely on the handle bar.
Check the new grip doesnt push against the throttle switch assembly.
Check the cables move freely
Check the cables dont have any frayed ends
check the cables arnt missing any of the plastic outer cover
check the cables a routed correctly and dont get jammed or pulled turning lock to lock

The most common cause of this is a dirty throttle body. If you follow your air cleaner hose to the engine thats your throttle body.When you take the air hose off you will see black stuff around your butterfly thats the bad stuff you can remove that by giving it gas or moving the throttle cables.and cleaning with throttle body cleaner! This will only take about 10 minutes

It means that when you are in drive gear but idle, that the idle rpm is several hundred rpm different from the nominal 'target' rpm. I would begin by removing the air intake hose to the throttle body and using a solvent clean the throat of the throttle body, both sides of the throttle plate (move the acceleator linkage for access to the throat and rear side of the plate) and also the port of the air passageway at the side of the throat which is for idle air input. Check that the throttle linkage moves freely. Also look for any vacuum hoses connected to the intake manifold to be sure none are disconnected, and also make sure the ball in pcv valve in one of those hoses is moving freely.
See how the idle rpm then 'rides'. If that isn't sufficient, then the idle control circuits need to be considered, but those have a separate fault code.

try getting a can of carb cleaner . removing breather and spraying gunk out of the inside of carb to free moving parts that are sticking. and also try spraying the outside moving parts of carb with penetrating oil

DETACH CABLE FROM THROTTLE LINKAGE..MOVE CABLE IN AND OUT OF CABLE HOUSING..IF IT MOVES FREELY,YOUR PROBLEM IS MOST LIKELY IN THROTTLE BODY/PLATE..YOU CAN REMOVE THROTTLE BODY..FIRST REMOVE AIR CLEANER,UNPLUG TPS,IDLE MOTOR AND INTAKE TEMP SENSOR..USE BRAKE CLEANER OR THROTTLE BODY CLEANER AVAILABLE AUTO PARTS STORES..DO NOT LET AND CLEANER GET IN TPS..YOU CAN USE A PLASTIC OR WOOD SCRAPER..SO YOU DON'T SCRATCH THROTTLE BORE AND CLEAN DEPOSITS FROM THROTTLE BODY/PLATE..HAVE SEEN THIS CAUSE STICKING OF GAS PEDAL..I HOPE THIS HELPS..WHEN DONE CLEANING,REINSTALL THROTTLE BODY AND RELATED PARTS

Clean inside throttle body with intake cleaner and a rag may be sticking because of gum and varnish buildup in take manifold. This should work, if it doesn't then you will need to check cables and make sure they are not locking up and moving freely. If that good then Throttle body will need to be replaced because this can be very dangerous with it sticking like you described. Good luck and thanks for using FIX YA