Talk Back = Feedback. Don't run it except to set your reverb, then turn it all the way down or off. If its locked on, disable it. If you want to listen to your output audio, get a separate walkie talkie CB and a set of totally sealed head phones.
Sometimes RF feed back can be cured by adding Snap on Ferrites (or chokes as they're sometimes referred to) just clipped on right were the mic cable goes into the radio. I wish I had a dollar for every time I preached that OTA and it helped someone. Search up "Ferrites Snap On" on Amazon. This site will not let me paste those links.
If your VSWR is too high, you could experience feed back. This can be checked with an SWR meter and should be below 3 when keyed with the mic gain all the way down.
A voltage sag or low current power situation can cause similar audio problems. Is your power supply up to snuff? A 3 amp supply may not be enough.