Your carburetor is starving for fuel and/or AIR, doesn't have anything to do with your oil or plugs IMO....by the way Walmart actually carries the Chrome oil filter....
First thing I would check is the flow from tank. Disconnect your fuel line to the carb (have a bucket handy) and see if the flow from tank is good, to make sure you don't have an obstruction FROM tank as in your liner breaking up....ipen and close petcock etc... If the flow from tank is bad, take your petcock off and clean well and drain tank.
I have found that routinely the fuel bowl gasket, or gasket membrane between tank & carb is varnished or dryed out from sitting all winter dry, allowing improper air into the carb. You can remove your air cleaner, then try and start it and see what happens as well.....
You can mess with the jets, needles and float all day long, but until this issue is resolved the problem will persist.
Carb kits are relatively inexpensive (fuel bowl gasket sets). Make sure to remove varnish from the fuel bowl ring and from the carb where it seats to.
Take your carburetor off (remove air cleaner) then there are 2 bolts that hold the carb on....CLEAN the entire carburetor and check that the main jet is clear first, use compressed air or a needle to clean ALL the tiny holes....if it is then it could the float needle partially plugged or an obstruction between there and the tank outlet.