Replaced charging port, still charging slowly.

Hi I recently replaced the charging port in my Note 3 N900T. The seller I purchased the replacement from ended up being one for the AT&T version but I've read that they are compatible. Once I replaced the part I tried to charge it and the phone is still charging very slowly and the same problems exist from before I replaced it including the phone keeps getting disconnected from the USB cable when it's plugged in requiring me to fidget with the power cord to get it to start charging even after trying multiple USB cables, and also my phone not being recognized at all when connected to a PC after trying multiple PCs as well. I'm not sure what could be effecting the phone after trying all the methods. Any help would be appreciated.

Thanks for the reply, I will have to use your suggestion to see if the battery is bad. Otherwise I solved the charging issue, somehow 3 of my USB cables all seemed to be bad. What are the chances. I found one that works and charging is no longer an issue. However, I have tried just about everything I could find out about USB connection to a PC and nothing works. Rebooting both the phone and the PC, turning USB debugging on/off, reinstalling android drivers on Windows 7, and trying different apps to no avail. I am certain that something is wrong internally with the phone itself. MTP always crashes when I attempt to launch and I can't seem to find a fix. I believe this might have been caused when I stopped Samsung Kies and attempted to uninstall it a couple months ago, but as it is permanent software for the phone it reverted back to samsung link. Both Kies and Link are no longer supported so I tried Smart switch and still no result. I think my only option now is to do a factory reset and hope that this is only a software problem.