Vehicle rpms would drop with car on drive and brake pedal applied.

Issue booster ruber membrane damaged and only noticeable as stated above. Confirmed applying smoke - cabin pedal foot area filled with smoke.

Changed brake booster... no need to undo brake lines. Remove battery, Battery tray, remove vacuum line from booster end, undo master brake cylinder (2), swivel it away towards front of car. Undo bolts from inside cabin (4), remove pin attaching pedal to booster (service manual recommends replaced, a 8 dollar piece). Manual also recommends replacing stop lamp switch.

Issue encountered - new booster not OEM... pedal seated about 1/4 of an inch short from switch plunger... pedal had plate that would contact with switch plunger....solution add a bolt M6 1.0 25mm long with bolt head on switcg plunger side.

Remove pedal (a bit of pain due to space and working upside-down)... locate where to drill hole in plate... used a M6 drill and tap. Cspture bolt with compression washer and nut from back and after adjusting bolt length ensuring stop lights activation added blue thread locker.