B&S 44N8770005G1 engine surging on a Husqvarna GT52XLSi tractor.

Hello
I am having constant surging issues on my 3year old Husqvarna GT52XLSi garden tractor with a Briggs and Stratton 44N8770005G1 engine. It happened about a year ago and then it “went” away on its own. Problem returned this year when I ran out of gas and refilled it.
When it’s idling, the governor goes crazy up and down. I brought it back to the dealer and was told the carb needs to be replaced and are asking 300+$. It’s got less then 200 hrs on it. Research showed that bad gas, spark plugs, fuel and air filter, bad/dirty carb could all be the problem. I changed all those parts except the carb so far. The fuel is always fresh since I use the tractor year round so the gas never sits for more than 2 or 3 weeks. I even use it to plow my driveway in the winter.
I also drained all the gas and filled it with 93 octane.
Used sea foam into the air intake like instructed by the dealer.
The sea foam worked for a minute and it ran normal (no surging) till it burned out, then it went back to surging.
Also, when I start to ride it it seems to become a little better but the surging will continue but not as much.
When I engage the blades it almost goes to normal (no surging), but you can still hear the engine is not running smooth.
My next step is to clean and rebuild the carb. I just ordered the rebuild kit so it’ll be a few days. Any suggestions till then.
Also any help with the carb assembly is appreciated. Thanks..
Luke.