Id start with simple first, fuel filter, plugged fuel line or dirt in the tank. Disconnect the fuel line from the carb and disconnect spark plugs, crank the engine, see if you have good fuel flow, if not work backwards from there.
I don't have all the attachments of some members, but I do have a finish mower, rough cut mower, light material bucket, snow blade and a mini hoe with thumb, great for picking up stuff, and of course my favorite, home made trash mover.
I had a local tractor shop do the work as I don't have the equipment or the tools to pull a motor, the work order says the part number is 263-78203-01 and they were $270.00 each. The work was done is July so the prices are probably out of date. I also installed an electric fuel pump last year...
I have a 2018 PT 425, with a Robbins, in the 3 years I have chased all the symptoms above and on the attached link, it wasn't till I replaced the coils, did my problems go away. Now she runs like a top and even starts in cold weather.