Ziggy, it sounds like you're not planning your approach properly.  do youself a favour and have a good read of the operations manual, and print out the pages withhe following charts:  

take off speeds v1 r  and 2,

Vref  speeds

min manouvering speeds


Ill forget the v1,2,r speeds for the moment since they're for takeoffs.  you're interested in the vref chart, which is your landing reference speed, and min manouvering speed charts which show the MINIMUM  speeds for each flap setting including 0

thie Vref  table lists flap settings, and landing weights, to give you the perfect Vref speed. which you add 5 knots too (vref+5) or up to 20 knots to if you have for example a 15kt headwind.

to work out your landing weight you'll have to calculate, or take note of how mcuh fuel you've used in your trip. so do that first OR write down several vref speeds and work it out as you come up for approach.

now ill assume you're doing an ILS approach.. heres what you should be doing. PLease reference the NORMAL LANDING diagram at the end of the operations manual.

you need to come in at a level altitude, and at around 200kts, with no flaps ( this will vary as per the min manouvering speeds chart.. reference it but for most landing weights you'll see its around 200kts). the altitude you level at for your landing circuirt is listed on charts for aerodromes but if you're not using one, lets just say 2000ft. As you decelerate below 200  to come onto your landing circuirt, or even if its  long straight in approach,  you need to extend flaps as per that chart. as you can see in the landing diagram you're basiclaly selecting flaps as speed decreases to the min manouvering speeds.. by the time you're ready to intercept the glideslope (from underneath!)  you should be down to flaps 25  and be holding your vman+10  speed stable. now if you're coming in STRAIGHT, you can select flaps 30 and stabise on VREF+5,  if you're turning base and onto final, stay on flaps 25 vref+10 (for a flaps 25 setting!)  to make it easier and more stable to turn.

so as you turn onto final , further slow to Vref+5 , and if you choose to use them, select flaps 30 (DO NOT USE 40, ITS NOT NEEDED AND GIVES SLOPPY ROLL RESPONSE , it is completely blocked out on real 727s now anyway for noise abatment and can't be used) , and slow to vref+5 for flaps 30  which may be 130-140kts, now begin decending on the glidepath. either as per vor/dme altitudes , or just plain ILS.

As soon as you start decending,  CONTINUE paying attn to stablising your speed.. this is the most important part to a sucessfull landing. you want to get it right on vref+5 whilst maintaining a constant  glideslope... if your  ILS needle is showing you a bit high, then as you start to decend more, GENTLY ease off the power to compensate and stop your speed running away.. this will help prevent the oscillations you speak off.

if you're heading a bit low.. the same applies only increase power.. its critical you smoothly increase power a tiny amount as you decrease change your decent. and 'balance' it, i.e if the speed starts dropping to 134 133 , dont slam the throttles up or you'll overshoot..  

Remeber.. whenever you start inadvertently slowing on approach, whilst keeping the same decent rate, your angle of attack increases.. increasing drag, further trying to slow you..   increasing speed lessens the angle of attack lessening the drag, so it results in a total overshoot of your vref, and you having to 'dive' for the runway in order to keep the decent. BAD

Your approach when stable should have you showing about 1deg pitch up.. not nosed down.  aim for this to be the case the whole time. if it's not and your nosing down , you've calculated something wrong . slow, or increase  your Vref so as to maintain a fairly level nose.

as you get down to the 20ft mart. and not a moment before.   gently flare only 1 or 2 degrees and watch your vert speed, making sure if its heading for 0 too quickly to relaxe the pull back.

practice all  this and you'll be on your way.. I personally still make the odd bounced landing or float along,  as the flare is just so difficult in this thing IMO, you either  flare too late and impact the runway slightly, or float from pulling back too far.

goodluck zig!