Pretty interesting that it runs fine once you depress the brake. So this doesn't happen any other time but when you're running downhill, uh? Note: Unburned gas would exit of the exhaust at stall.

It's pretty rare but you could focus on a thick-gauge yellow (I think its yellow, maybe red) wire running throughout the mower. Sometimes the wire gets crimped or crushed somehow, looses its insulation in a place and touches ground under certain strange circumstances. If that wire does touch ground at all, the engine spits, sputters and might stall. When you depress the brake, the long brake/clutch linkage may move the wire away from ground temporarily.

LONG SHOT I think, but its what comes to mind. Hope this helps. Tape the wire and secure to something solid with ziptie-straps.

It is possible to have a kill wire, carb solenoid wire etc. shift as you change slope. Water in the bowl of the carb is another common cause.

Thanks for the quick reply! I'll try this when I get a chance.. But the reason I think the seat switch is not the case is because it also happens when I let the brake go while in Neutral gear. Please let me know if this should also be happening in Neutral. Thanks!

It will happen regardless of the "gear" the engine is in. There is no sensor on the transmission to tell if the trans is in Neutral. Some machines have a switch to sense REVERSE gear, on the trans or on the shifter linkage. But not neutral.

I had a similar problem on a 25HP Generac engine. I had bumped the rollover switch off vertical when I changed the oil filter. It is a tubular device approximately 3/8" wide by 1" long.

Thanks Mownie, you were spot on! It turned out that the seat was just a little out of position from the 'main' pressure point of my butt vs the seat switch. Although it looked fine, I readjusted the seat and it runs like a champ again. Thanks again, so glad I came across this forum!

They say that even a monkey banging on a keyboard will eventually "spell a word" (so it goes with my "input").
"Help forums" depend as much on feedback from members who have gotten a solution as well as members who give of their time to try and provide solutions.
Thanks for the positive feedback.

we are having the same issue on the same model as jchin34.. when we are going downhill/or on a slope the mower bogs down and starts to act like it is going to stall.. but if you put the clutch in when it starts doing that then you can "save it" from stalling. It revs really high for a second but then you can continue to mow until you are going downhill or on a slope again. But if you don't put the clutch in when you hear it starting to bog down then it will completely stall on you but start right back up with no issue.

We have tried replacing the deck belt (which really needed replaced anyways), the ignition switch and the fuel filter which none of them solved anything but it did make it mow a little bit better.

Everyone is saying that it could be the safety switch on the seat and to bypass it with a wire. Do you think this could be the same issue? & has it done it since jchin34?

We are both only about 150lbs that use the mower so im sure our weight shifts when were on the hill/slope.

OK, I found and fixed my lawn mower. It's the carburetor. The solenoid that opens to let gas into the carburetor is the problem. The little rubber "seat" came off the solenoid plunger and gets stuck at the gas intake of the carburetor. This allowed a little gas in to the carb but when I throttl up doesn't allow enough gas into carb.

Simple fix. I cleaned surfaces an crazy clued the rubber tip to the end of the plunger of the carburetor.

IT RUNS LIKE A CHAMP.