Misfire and strong sulfur smell from exhaust

[Homeowner A]

Coleman UT 400 has a strong sulfur/emissions smell from exhaust all the time.  Kind of like it’s running rich and a catalytic converter is trying to make it run cleaner so it smells bad. Also misfires when warm. Idles fine. Full throttle fine. In between it cuts out. Do these have catalytic converters?  Almost acts like it might be clogged if so. 

[Joe Breaux]

Cats don't work like that..what kind of fuel are you using?  Old ? Any additive in it?  Like octane booster? Should you be running premium? Put you hand behind outlet, feel pressure?  If it's weak, there may be a blockage. Any smoke on start ?

[Homeowner A]

10 minutes ago, Joe Breaux said:

Cats don't work like that..what kind of fuel are you using?  Old ? Any additive in it?  Like octane booster? Should you be running premium? Put you hand behind outlet, feel pressure?  If it's weak, there may be a blockage. Any smoke on start ?

Fresh 93 octane.  No smoke on start.  What outlet exhaust if so, yes it has pressure.  

[Joe Breaux]

Any oil leakage?

[Homeowner A]

2 minutes ago, Joe Breaux said:

Any oil leakage?

No oil leaks

[Joe Breaux]

Got me..if it was running rich it should smoke black.and it shouldn't smell like sulphur..if it has exhaust pressure there no restrictions. Good fuel...I'm out of ideas.

Pull the spark plug..if it's wet or black it's flooding.  Should be a dry tan color

[Homeowner A]

2 hours ago, Joe Breaux said:

Got me..if it was running rich it should smoke black.and it shouldn't smell like sulphur..if it has exhaust pressure there no restrictions. Good fuel...I'm out of ideas.

Pull the spark plug..if it's wet or black it's flooding.  Should be a dry tan color

What is 7 in this parts diagram?

https://parts.colemanpowersportsusa.com/parts/utv_side-by-side-parts/outfitter-400_ut400/muffler-parts