Ok guys I have a few questions. First off I'm relatively new to mud motors. I have had a 6.5 hp do it yourself long tail on a small jon boat and then this 31 hp go devil long tail. This one seems to be giving me more problems but it is older and I'm new to this. First off I had the problem where the motor was not running good at all and stalling out. Realized I did not have a gas cap with a breather on it. So i got a new gas cap and bam problem fixed. Then I'm out a few days after getting it and I was running WOT and hit a log and it jarred the engine out the water the engine kept running but Immediately sounded different and I had absolutely zero throttle response. In fact when I would try to give it throttle it would start to stall. So i limped it back to shore. I pulled the top plate off once I got home and seen that the rod connecting to the throttle was off and just laying there. Also I realized I lost a spring in the back of the throttle setup on the engine. So i ordered a rreplacement and decided I should get spark plugs and a fuel filter while I was at it. So i changed the fuel filter and then I was changing the plugs only to realize the guy I bought it from had the wrong plugs in it (he had the short ones instead of the long ones for ohv) and man they were black. So i replaced the plugs with new correct plugs. Now the motor starts and idles good. Still no throttle response. Any ideas? Also I let it run for around 4 or 5 minutes in my driveway. After that I noticed inside the muffler it was glowing red. Is this normal. It was very shady and cloudy where I was at maybe that's why I noticed it. Also where the prop attaches to the shaft there is a stainless steel piece around 2 or 3 inches long. That was warm. Not hot but warm to the touch. Is that normal after a few minutes of running at idle out of water? Could this be a carb issue? He claims to have just had the carb cleaned and prior to hitting the stump this engine ran great. Could I have knocked something loose and that fouled out the wrong plugs that were in it fast? Any help is appreciated. Thanks.

I know you have new plugs in it so it may be hard to tell if it is running lean, but it sounds like it. For kicks try a different fuel source.

I thought the bigger motors like these have a fuel pump too. It might have damaged it causing a lean condition which explains the extra heat.

Which model is this? Briggs or Kohler? Maybe I missed it.

Also do you have a primer bulb off of your tank? Did you try with your gas cap off again to rule this out? It might be all related to your original issue and the log just coincided with your fuel pump going bad.

Extra Reading:
http://www.advrider.com/forums/showthread.php?t=801022