ALT HDG TRACK DEV DURING RADAR VECTORING FOR IAP ILS APCH IN A NIGHT OP.

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WHILE BEING VECTORED FOR THE APCH TO RWY 22L BOSTON; WE WERE AWARE OF WX (RADAR CELLS) E OF BOSTON. WE WERE ASSIGNED A HDG OF 190 DEGS TO INTERCEPT RWY 22L LOC. THE CAPT; WHILE MAKING THE R TURN TO THIS HDG; WAS CONCERNED THAT IT WOULD LEAD US INTO THE WX. HE CEASED THE R TURN AND BEGAN A TURN BACK TO THE L. THE CAPT ASKED THE FO TO TELL APCH WE WERE UNABLE THE 190 DEG HDG. THE FO WAS UNABLE TO HEAR THE CAPT'S STATEMENT SINCE HE WAS IDENTING THE LOC. APCH THEN CONTACTED US STATING THAT WE WERE GOING TO CROSS THE LOC AND ASSIGNED US A 240 DEG HDG TO REINTERCEPT. THE CAPT TURNED TO THIS HDG. NOW WE WERE L OF THE LOC AND GS CAME ALIVE AND PEGGED OUT ON THE BOTTOM. WE HAD BEEN CLRED FOR THE APCH AND TOLD TO MAINTAIN 3000 FT UNTIL ON COURSE. WHEN THE LOC CAME ALIVE THE CAPT STARTED A SLIGHT CLB RATHER THAN THE REQUIRED DSCNT TO CATCH THE GLIDE. I AM UNCLR AS TO WHETHER THIS OCCURRED AS A RESULT OF INCORRECT EFIS PROGRAMMING OR WHETHER THE CAPT PUNCHED OFF THE AUTOPLT. PASSING 3100 FT THE FO TOLD THE CAPT TO WATCH HIS ALT. THE PWR WAS ALL THE WAY BACK IN ORDER TO SLOW TO THE ASSIGNED 175 KT SPD. THIS FACT; COUPLED WITH THE SLOW CLB; RESULTED IN THE AIRSPD BLEEDING OFF TO 125 KTS WITHIN A MATTER OF SECONDS (FLAPS WERE AT 25 DEGS AND GEAR UP ON AN LGT). WHEN THE CAPT NOTICED THIS HE IMMEDIATELY SHOVED THE PWR FORWARD AND ANNOUNCED MISSED APCH. THE FO CONTACTED APCH AND TOLD THEM ABOUT THE MISSED APCH. WE WERE ASSIGNED A HDG OF 310 DEGS AND MAINTAIN ALT OF 3000 FT. SINCE THE CAPT BEGAN CLBING WHEN HE ANNOUNCED THE MISSED APCH; WE WERE AS HIGH AS 3800 FT IN A MATTER OF SECONDS BEFORE HE DROPPED THE NOSE. THE AUTOPLT WAS DEFINITELY OFF AT THIS POINT BECAUSE OUR ALT VARIED BY PLUS OR MINUS 500 FT AND HDG PLUS OR MINUS 20 DEGS UNTIL THE CAPT FINALLY ESTABLISHED CTL. AUTOPLT WAS REENGAGED WITHIN APPROX 10 MINS. AFTER LNDG THE FO BEGAN TO DIAL IN THE GND FREQ AFTER WE WERE CLR OF THE RWY. I STATED THAT WE WERE TO REMAIN ON TWR FREQ. THE CAPT ACKNOWLEDGED MY STATEMENT AND THE FO PROCEEDED TO CONTACT GND. WE WERE THEN TOLD TO CALL THE TWR WHEN WE GOT INSIDE TO EXPLAIN THE REASON FOR THE MISSED APCH.