C172 IFR ENRTE HAS NMAC WITH VFR ACFT ON ATC FREQ.

Narrative

I WAS ON AN IFR FLT PLAN FROM ILM TO AYS; LEVEL AT 6000 FT MSL. WHEN I FIRST CHKED IN WITH FLORENCE APCH; THE CTLR SAID HE WASN'T PICKING UP MY XPONDER. A FEW MOMENTS LATER HE SAID HE WAS RECEIVING MY XPONDER AND ALT READOUT. AS I WAS APCHING FLO VOR ON V139 THE CTLR ASKED ME WHAT ALT I WAS AT. I REPLIED 'LEVEL 6000 FT.' THEN THE CTLR CALLED TO THE OTHER AIRPLANE 'TFC...' AND DID NOT COMPLETE HIS CALL. I IMMEDIATELY SAW AN AIRPLANE HEAD ON APCHING FROM MY 11 O'CLOCK POS AND TOOK EVASIVE ACTION; MISSING THE ACFT BY LESS THAN 500 FT HORIZ AND ZERO FT VERT. THE OTHER ACFT WAS A C172 OR C182 AND PASSED OFF MY L WING. THE OTHER ACFT CALLED 'TFC IN SIGHT AND THEY ARE VEERING OFF.' THE CTLR THEN CANCELED FLT ADVISORIES WITH THE OTHER ACFT. I BELIEVE THEY HAD VFR FLT FOLLOWING. AT NO TIME DID I RECEIVE TA'S OF ANY KIND. THE CTLR THEN HANDED ME OFF TO SHAW APCH ONCE I WAS ESTABLISHED ON V157. PREVIOUSLY I DID HEAR THE FLORENCE CTLR MENTION ON THE RADIO THAT HE WAS HAVING POTENTIAL DIFFICULTY WITH HIS EQUIP BUT HE NEVER MENTIONED IT TO ME. MY CONCERN IS INTERMITTENT APCH CTL EQUIP AND THE POSSIBILITY THAT THIS APCH CTLR WAS NOT PERFORMING HIS FULL RESPONSIBILITY AND DUTIES REQUIRED. MY EVASIVE ACTION WAS A PROMPT 60 DEG BANK TO THE R UNTIL COLLISION AVOIDANCE WAS CERTAIN.