Cub Cadet lt1042 acts like out of gas with full tank! HELP!

I have an 06 cub cadet Lt1042 25 hp kohler engine riding mower. has 230 hours. got it used from parents. they always had one issue with the valve cover gasket leaking oil onto the muffler and burning off. (never affected it) I got it and first season ran great. stored it for winter, 2nd season mowing it would run for about 1 hour and start choking and act like it was running out of gas. I would shut the pto off and it would straighten out. Had to let sit for 20 mins then mow again. would only get 45 mins to an hour out of it before it would start again. This year it seems to be worse. only getting 10 to 20 mins out of it. Replaced valve cover gasket, fuel pump and fuel filter. seemed to run great right after having the fuel pump and filter done. The second mow after that though, back to the problem! Will run good until I hit a slight incline or bumps in the yard or heavy grass. (sounds just like it's running out of gas but has full tank) when this happens, if i kick the deck up and down while pto on it will act HORRIBLE! backfires and coughing! If i shut the pto off let it idle it will straighten out and will run with blade off ALL DAY! It has the gas pedal forward and reverse..if I push on the reverse and let it go quickly will also start choking and acting up! PLEASE HELP!! I am running out of money and patience with this thing!! also, when we first got it when you initially started it you would pull choke out and as soon as it started you had to push choke in quickly...NOW you have to run on half choke and SLOWLY push it back in ??? and when it starts acting up if I floor the gas pedal it will spit and sputter and eventually stall completely...

I wonder what is floating around in the bottom of the carb bowl. Sounds like you need to remove and clean the carb.