Serving Different Pages - Does it efect listings

My site needs to serve different pages .. Will it effect my listings...

[webjp]

My site gets a lot of traffic and as a result I need to serve different pages to distribute the load, does it affect my listings?

My site used to appear in top 10 for a very competitive keyword, it still did come in top 10 for about 2 months even after I started serving different pages (though there was some fluctuation but it settled down). But after the backlink update my site dropped from 10-20. I am concerned because my site is one of the best in the business with good page rank and properly optimized and still it is not reviving from the slump (My opinion is the sites which are before mine are nowhere in competition in terms of popularity and business that we make…). So all I am left with to justify the drop in position was the serving of different pages, though it was not a problem before!

I would appreciate any insights.. THANX IN ADVANCE.

JP