You need to go back and start over again. Don't worry ab out the tank right now. Remove the fuel hose from the petcock, and see if you get good gas flow. If so, you are ready to move on. If not, you need to remove the petcock and check the filter on the inside. It may be plugged up. There is also a removable sediment trap on the bottom of the petcock that should be removed and cleaned. After cleaning everything (I use spray carb cleaner) put it back together, and see what happens. If you now get good fuel flow, time to move on. If not, the last thing you can try is soaking the petcock in Seafoam for a couple of days. If that doesn't work, you are probably looking at a new petcock. Honda petcocks are riveted together and cannot be taken apart.
Once you have good fuel flow from the petcock, you have eliminated that as a problem. Next, install a new (clear if you can find one) fuel line directly from the petcock to the carb, without a filter, and ride the bike. If the performance has not improved, the next step is to remove, completely disassemble and thoroughly clean the carburetor, including all passages. The small E string from a guitar works great for cleaning jets and other small passages. Blow everything out with spray carb cleaner. Wear a face shield to avoid getting the carb cleaner in your eyes. Check the vacuum diapgragm for any holes and make sure it fits properly around the edges. Put the carb back together and hook everything up. Make sure the throttle and choke cables are connected and operate properly. Make sure the fuel line is full of gas. There should be no air pockets. Now ride the bike again. If it STILL does not run right, and if you are sure you cleaned the carb properly, you have pretty much eliminated the fuel system as the problem.
Next, get 2 new NGK spark plugs of the correct type, connect them to the plug wires, but do not install them. Lay them on the engine somewhere so they are grounded. It is best to do this in the shade, so you can see better. Turn the engine over with the starter. Check both plugs. You should get a nice fat blue spark from both. If you do, the only things left to check are valve adjustment and compression. Make sure the valves are adjusted properly, then check the compression. It should be 160 psi or higher. If you did not get a proper spark, repost after doing everything but the compression test. Even though the ignition system on the Rebel is simple, there are a lot of things to check. I don't want to get into all that here if it is not necessary.