Originally Posted by Boosted_Ion
OK, that narrows down the possibilities a bit, One more question- has the radio ever been removed or replaced on your car? (more on that in a bit)
Still on THAT radio it's most likely an antenna connection issue.Although certainly it could still be internal to the radio, the external items will need to be confirmed/repaired first.
There is an antenna lead-in inter-connection in the RH kick panel area that may have a poor or corroded connection.
There is also a braided ground strap betweeen the radio and the Instrument Panel Fuse Block that MUST be present (and connected properly) to insure sufficient ground plane for the antenna. Sometimes when the radio is R&R this ground strap doesnt get reconnected. This is "historical baggage" from GM that goes all the way back to the mid-80s GM ETRs where poor reception and radio noises were caused by such a ground strap- and since then it's become common practise to remove them or leve them off. But in the ION's case leaving off the strap results in a significant loss of antenna reception strength.
Anyways you can also install a temporary "test antenna" to the radio (leaving it all including the mast under the IP) and drive the car using that for a few days to see if the condition ceases. Does it happen daily??