I started my lawn mower for the first time this year and it ran great for about an hour and I shut it off. When I restarted it it ran fine but the setting for the throttle is off, there's a choke, fast , slow and off, well now it only runs when is on the choke setting and it runs about half idle if I move it at all to any slower setting it dies. When it's running it seems to surge a bit going up and down in rmps I adjusted some of the screws on the linkage but j can't get it to really rev up, there also seems to be a little black smoke coming out of the muffler I'm kinda senscing it running to rich. Also there's a small leak coming out of the fuel line right buy the fuel tank, if it was sucking air would that cause it to not rev up? It's a older self propelled Toro. I checked out the throttle cable and it looks good.