LT1000 Running Rough
I inherited an older Craftsman LT1000 when I bought my house a few years ago. I've been changing the oil & filter, fuel filter, air filter, spark plugs regularly and it's been running great. Did the same thing this year.
Had it up and running fine last weekend. There's a notch in the throttle that says "Throttle here for mowing" (or something similar) and I had it set there while mowing. I inexplicably raised the throttle past that point while mowing. I immediately realized what I did, but the engine start sputtering and died before I could get the throttle back down.
I tried to restart the mower but it wouldn't start, so, I let it sit for a while and then got it running. When it started, it was spitting out a lot of grey/white smoke, so I let it run and run. As it ran, however, it was louder than normal, with the occasional "pop". I pulled the spark plug, which was new, and saw that the tip was black and covered with soot. So, being that I had a spare spark plug, I replaced it. But when I started the mower back up again it's still running loud with that "popping" sound.
Also, I should mention that when I put it in gear it's moving slower than normal, and if I engage the blades, I can hear that they're not moving at normal speed.
Any advice would be much appreciated. I can't easily get this into a repair shop, so anything I could do on my own would be great.