Dang, now I got problems too!
Last time I had my sled ('96 550 cougar) out I just ran it up and down the road a couple times and it was very lethargic. I figured the plugs were shot but didn't have time to mess w/ it so I just ran it in the shed and called it a night. Today I finally got it out, tossed some new plugs in it and it was good as new. We went for a ride and it did great for about 2 hours of trail riding, so good infact we decided to load it up on the trailer and take it out tomorrow for a day hauling the kids up and down the mountain snowboarding.
Where I park my sled trailer it backs up to a steep hill. This year the hill had about 3' of fresh powder on it so of course I had to blast up it instead of just pulling the trailer into the drive to load. The little sled screamed up the hill and as it topped over the apex to the flat behind the trailer it flat died. I fired it back up w/ 1 pull and it idle's like a champ but won't take any throttle. You give it some gas and it immediately bogs and dies. The new plugs still look great, and there is heet in the tank. I am mostly baffled because it ran GREAT for 2 solid hours. I parked it for about 20 minutes and fired it right up and did some laps around the yard and it was still running great. I blazed up that steep powder covered hill and it did great right till it crested the top and then blaaaahhhhh.
So what would cut out all of a sudden like that? I am thinking I will probably just drop it over at 90's and older Monday and let him go through it but it would be nice to see what others have experienced. It seems to have all of the big three (fuel, spark, air). Could the reeds fail suddenly and cause a problem like this?
If it idles until you give it some throttle, the first thing I would check is the TPS and the throttle cable for excess slack. It has been a while since I worked on cats, but some of them you could just unplug it to check it other years they had a electrical plug it the tool kit you plugged the wires into to bypass the kill switch.
Safety cut-off switch
Lots of Cats have this problem, and you can disable it like onstep says by shorting out the wires. You won't have stuck throttle protection after that, so always check your throttle or replace the throttle lever assembly.