Will a Mishiki Pueblo Mountain 20 in frame hold my weight. I go about 330
First congratulations for getting back on a bike. As others have stated the typical weak point will be the axles and wheels. I would recommend having the wheel bearings serviced by your local bike shop. Ask them to check the spoke tension as well. I've seen quite a few low end wheels with poorly adjusted bearings and almost no grease in the hub. I would then run the tire pressure to the max spec on the tire sidewall. Even then they are likely only suitable for pavement or bike path use. If wheel problems occur consider investing in a set of wheels designed for a tandem bike. They are capable of supporting 2 adults. While they will cost more then your current bike you can use them on your next bike when you upgrade. Another option is a used LandRider auto shift. They are frequently listed on Craigs List for under $200 in my area. They are rated for 350 pounds