AN SMT PLT HAD TO RETURN LAND WITH AN ENG PROB.

Narrative

WE WERE ON AN IFR FLT FROM 1C2 TO PIA. WE LEVELED OFF AT 6000 FT AND SHORTLY AFTER; THE AIRPLANE STARTED TO SHAKE. AT THE SAME TIME; THE PROPS WENT OUT OF SYNC. ADJUSTING THE PROP CTLS; THROTTLES; AND MIXTURES DID NOT HELP. ALL ENG GAUGES APPEARED NORMAL. I REQUESTED TO RETURN TO 1C2 FROM CTR AND WAS TOLD THAT I WOULD HAVE A CLRNC SHORTLY. I EXPLAINED THAT I NEEDED A TURN ASAP TO MAKE A PRECAUTIONARY LNDG. I WAS CLRED FOR A R TURN; DIRECT NEW LENOX. I WAS THEN ADVISED TO CONTACT CHICAGO APCH. THE APCH CTLR ASKED IF WE NEEDED TO DO AN APCH. I ADVISED THAT WE WERE DIRECT NEW LENOX (WITH RNAV) AND WOULD NOT NEED THE APCH. THE CTLR THEN GAVE A VECTOR OF 360 DEGS TO GO DIRECT. I WAS ON A HDG OF 030 DEGS (NAVING WITH THE RNAV) AND WAS GOING DIRECT NEW LENOX. AS WE DSNDED TO 4000 FT; WE WERE VMC AND MY POS WAS CONFIRMED WITH GND REFS. THE CTLR THEN GAVE A VECTOR OF 340 DEGS TO GO DIRECT AND I EXPLAINED THAT THE ARPT WAS IN SIGHT AND WE WERE HEADED DIRECT ON OUR PRESENT HDG. THE CTLR THEN STATED HE HAD THE WRONG ARPT; APPROVED A FREQ CHANGE; AND GAVE US TFC INFO. AN UNEVENTFUL LNDG WAS MADE. I FEEL A PRECAUTIONARY LNDG WAS PRUDENT FOR SAFETY AND THE DEP ARPT WAS THE CLOSEST. THE CONFUSION ABOUT THE AIRPLANE'S POS RELATIVE TO THE ARPT COULD HAVE BEEN ALLEVIATED IF I HAD INFORMED THE CTLR THAT I WAS RNAV DIRECT AND ON COURSE UPON HIS FIRST VECTOR.