Bluetooth audio with ipod on iphone 4 doesnt sound good most of time

When I play my music on my iphone 4 through my car stereo via bluetooth I find most of the time the audio just sounds like a low grade recording even though most songs are in 320mbps or AU lossless. If I plug in the iphone 4 with USB cable to the deck the sound improves to the way it should sound. When I unplug the USB cable and revert to bluetooth again the sound deteriorates slightly to sounding like a bad recording again. The audio seems to only be affected in the highend of the audio spectrum. Cymbals and hithats in the music seem to sound just slightly distorted or like they are under water.
Since I have upgraded to IOS 4.3.1 I have had nothing but problems in addition to the above problem. I have had:
high pitched squeals at times during audio playbacksongs skipping like a scratched CDbad bluetooth audio during ipod playback (BT phone quality is excellent tho)battery drain seems much greater now (although a hard reboot fixes temp)clicking and pops during USB cable playbackslight stuttering during audio playback via bluetoothhome button sometimes not fully working (have to press a number of times to get response)
I have done a hardware reset many times when these issues happen which sometimes takes care of some of the issues but the issues just keep appearing shortly afterwards. I also have barley none if any apps running in background.
I just find that this update from apple *****. Surely Apple can do better than this.
Btw, my car stereo is a JVC KW-XR810 which is totally compatible with the iphone 4. Anyone else having the same or similar problems like mine, especially with bluetooth audio. I have done quite a long search on this discussion area and do find others with some similar issues but not much concerning BT audio. This quite frustrating.
iphone 4 iOS 4