MLG ACR FLC CHALLENGED BY APCH CTLR WHEN ASSIGNED SPD TO OM IS OBSERVED SLOWING. FLC CHALLENGE CLRNC; BUT INCREASE TO REASSIGNED SPD. PASSING OM; FLC REDUCE SPD FOR LNDG CONFIGN. FLC CITES CONTRIBUTING FACTORS AS FREQ VOLUME CONGESTION; NUMEROUS VECTORS AND SPD ASSIGNMENTS.

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HELD DURING ARR INTO BOS. EXITED HOLD WITH MULTIPLE VECTORS AND AIRSPD CHANGES. APCH CTL FREQ VERY BUSY WITH MULTIPLE XMISSIONS TO ACFT. APCH CTL MISTAKENLY VECTORED OUR FLT THROUGH THE LOC AND THEN VECTORED US BACK TO RE- INTERCEPT LOC; LAST INSTRUCTION AS UNDERSTOOD BY CAPT AND FO WAS TO SLOW TO 170 KTS CLRED FOR THE APCH. APCHING THE OM AND GS INTERCEPT (4.7 NM FROM RWY 4R) STARTED TO SLOW ACFT AND CONFIGURE FOR LNDG (140 KTS) APCH CTL CALLED US TO INCREASE OUR SPD IMMEDIATELY TO 190 KTS OR STATE OUR INTENTIONS. AS SOON AS WE REACHED 190 KTS; THE CTLR AGAIN CLRED US FOR THE APCH AND TO CONTACT TWR. IMMEDIATELY SLOWED TO APCH SPD AND COMPLETED LNDG. MISCOM BTWN APCH CTL AND OUR ACFT OCCURRED. EITHER APCH CTL TOLD US TO MAINTAIN 170 KTS TO THE OM OR HE NEGLECTED TO ADD THAT TO HIS XMISSION. BOTH PLTS CONFIRMED THAT WE WERE CLRED FOR THE APCH AND THAT WE HAD NOT HEARD TO MAINTAIN 170 KTS TO THE OM. IN ANY EVENT; USING NORMAL PROCS REQUIRES US TO SLOW AND CONFIGURE THE ACFT APCHING THE MARKER ON GS. WITH MULTIPLE XMISSIONS DURING THE APCH IT IS ALMOST IMPOSSIBLE TO GET CLARIFICATION IF A MISUNDERSTANDING OCCURS. SUGGEST A SLOWER FLOW TO ARPT.