Falling "in and out of stereo" implies that:

-either your local station has not got their EOS/RDS settings right
- your tuner has a bad antenna earth
- your tuner has a bad signal ground
- your tuner might be talking to an active antenna with a bad power feed

Have a go at those first: if your antenna is short and has a coil wrapped around it, it's probably active and you need to wire up a good supply to it - the empeg tuner module doesn't do this.