Electrical problem, HELP!

I hope someone can help. This problem occurs after the car has warmed up to full temperature. My windows, wipers, sunroof, and fan run at double speed. As much as I like the windows to go up or down in only 2 seconds I don't want the motors to burn out due to excess voltage. Also, the speakers will shut down when this happens. The stereo is still getting power since I can still see the radio station or see the CD timer continue to count up. I had the accessory bus which attaches to the battery cleaned and repaired, I still have the same problem. When the engine slows down to idle speed (700 rpm) everything works normally, usually. As soon as the rpm's are raised this problem will kick in again. Sometimes if I draw enough power by running the headlights and turning the fan speed up the speakers will work again, until I lower the fan speed. Everything is original equipment, no rewiring done. Please help so I don't empty my bank account at the mechanics garage.

Have you checked the voltage in the car. At the battery posts and at the accessory outlet (cig lighter). It shouldn't be much over 13 volts, under 15 volts for sure. Sounds like something is gone bad with the alternator but it seems like the battery should cover for you.

sounds like the regulator in the altenator went bad or a short
the regulator clips the voltage at a programed level japanese regulators usally set at about 14.5 vdc. unregulated an alt can put out alot more
old cars used alt and generators w/ external regs
70s thru 90s cars used ic (integrated curcuit) alts with a built in regs
i hear that newer cars use a non ic alt that the car's computer controls
the regulating functions
put a volt meter accoss the pos and neg battery terminals while the engine is running it should read 14v to 14.8dc
15 is a lil too high but not too bad
13 to13.9 low but acceptable
under 13 remove and have benchtested
test battery too while ur there observe the volt meter while the car is cranking bettery voltage shouldnt srop more than 2 volts if more either the battery is bad or the starter is bad check the battery 1st by using a load tester (like 60$ 4 cheapo 1) or take it to auto zone they do it 4 free if the starter is going bad it draws more current hence the volts drop (ohms law) always assume its the battery 1st since its cheaper and usually easier to get to than a starter

i dont think its ur battery becase it will reduce its potential not increase it if it looks swelled its being overcharged

I did some Voltage measurements on my car for a bench mark. Here is what I found.

Engine off/cold 12.36

At the accessory socket engine temp normal
idle-varies 1000rpm 1500rpm

All off 14.11 14.11 14.11
Headlight on 14.10 14.13 14.12
AC on 14.02 14.02 14.02
Head/Ac on 13.94 13.94 13.96

At the Battery

All off 14.08
Headlight on 14.01
AC on 14.00
Head/Ac on 13.95

I don't know what this proves other than the voltage should be around 14 volts. If it isn't, I agree that the regulator should be checked.