2006 Polaris Classis, starts right up idles fine. Gave engine ample time to warm up. When I depress the throttle to engage the drive the engine sputters and stalls. I can bring up the RPMs to about 4K if done real slowly but sled never engages and I cannot get over 4K RPMs before stalling out. Release throttle and engine ides perfectly. Tried forward and reverse. Tried fuel switch in "normal" and "premium". Last week rode 200 miles no issues. What and I missing??

Ice in the carbs?

Turned heater on in garage this morning. Going to check progress

Could take heat gun to the carbs to speed up warming process

does it do it if the choke is 1/2 on?

sounds like a carb issue. mine did that for a bit. pulled carbs apart cleaned and blew out with compressed air.

Symptoms worse with choke 1/2 on

Replaced plugs as they were fowled, although I think that was from the sled not not being able to get above 3500RPM before stalling. Anyway replaced. Same effect. Temps have been very cold up here -20s so added some "Heet" to the fuel system to eliminate ice in fuel system.

When idling it purrs like it should, just cant get it to go.

Possible fuel pump diaphram issue??? Are fuel pumps fairly easy to rebuild or just buy a new one. Can I just disconnect from carburator side and crank machine it see if fuel spills out?