i dont think you are supposed to loosen up dramatically when you reach the final table, but i guess a lot depends on your relative stack size. I dont play the big tournaments but have plenty of the 90 man final tables under my belt, and i always seem to do well tightening up at the final table (as im pretty lose around the bubble - note the bubble on these 90 man turbos is justbefore the final table). anyway i digress. i tighten up and let poeple knock each other out and i wait. wait for that one spot, where i can substatially add to my pile (like someone trying to steal my blind when i have 77+, A9+.
The when its down to four, i basically play ICM. Steal alot with good/medium hands (say on button A6+). And raise big - dont frig around like raising 3XBB when you only have 8BB.
Luck is also a factor and if you are making the final table as regularly as you say, it wont be long till you win a couple of big ones. gl