Got a little problem. I picked up an MTD lawn tractor the other day. It has been setting up for a while. It has a 20 HP B&S Intek engine. I flushed out the gas tank and rebuilt the carb after vatting it in carb cleaner. I blew out all the jets and even ran a small wire down every hole I could. It surges from the minute I crank it. If I pull the choke out about half way it stops. As a matter of fact it even seems to have a little more power. I am at by wits end over this one. It did have a couple of "restrictor plate gaskets" with the kit but not on the engine. Any help or tips you can think of would be greatly appreciated.