buffalojim

Greetings,
I bought a package of one owner MXZ's. One is a 98 440 fan and the other is a 99 600. They look new and each has less than 900 miles. Problem... The 600 worked fine first time out for about half dozen starts' then I shut it down and once restarted could not get above 3000 RPM. The key light was flashing as well. Manual says DESS sytem malfunction. I took it to Skidoo for reprograming and a new teather key. I had the old one reprogramed and the new one done as well. Both were working when I left the dealer. At home I took it for a ride and after a 1/2 hour shut it off. Came back, tried to restart and nothing doing. I could get it to run for about 3 seconds at an idle after choking but that was it. I put the other teather on and it would run but again the light was flashing and I could not get above 3000 RPM. I switched back and forth between the two teather keys and they acted the same each time. What is going on? Any ideas on cure and cost of such. I don't want to waste anymore of this excellent Pacific NW winter. Thank you for your help.