Fm Transmiter

i have built an fm transmiter consist of two stages. One is oscilltor and another is power amplifier.the oscilltor stage works very well, but when i couple the amplifire stage with it, the out put frequency changes the total out put power i obtained is more less than the oscillator stage.
Can any one help me how to tune the power stage to the oscillator frequency.
Regards..

A circuit schematic would be really useful, words don't describe circuits very well.

The second stage is not intended to increase the power. It simply isolates the oscillator from the antenna. This improves the stability of the oscillator.

Of course the second stage can increase the power if it uses enough supply current.

OP didn't say what his design is, so I used the one that I recently built.

To tune the output amplifier of my FM transmitter i made a VHF AM detector which I connected to my DMM with very short wires. The output voltage was nearly 1V when it had a short antenna and was about 1m from my transmitter's antenna. The tuning was very broad. When peaked at 98MHz the output was only a little lower at 88MHz and at 108MHz.
Here is the schematic of my detector: