02 Sienna- alternator and battery

[WeileMom]

Hi,
I have a 2002 Toyota Sienna XLE with around 58,000 miles on it.
After a recent move from California to Illinois I came out to my car to find that it wouldn't start. A tow truck charged the battery but it wouldn't hold if the car was turned off so I followed the truck to his service station.
It was decided that my alternator had gone bad. They said that the battery also was weak so both parts were replaced. About 2 weeks later my car would barely start again so I took it back to the service station. They decided that the battery they installed was bad and replaced it.
Its now about 3 weeks later and I've noticed that when I start my car it hesitates and then the engine revs really high and then slows. It didn't use to do this. Also, I noticed the overhead light dimming slightly right after it started. This made me nervous because the electronic components (power door, power lock, etc) started to go when I had the problems before.
Should the car go back to the service station? Or would it be better for me to get it checked out by a Toyota dealer?
Is there something else that could have been overlooked?
Thanks for any help,
Nicole

[lsac]

I changed OEM battery from 98 Sienna in 7/05. That battery had lasted for nearly 88 months. I noticed the problem with weak starting power. A voltmeter showed cranking voltage dropped below 9V. After battery change, high speed starter has sounded well since.

Always change battery first. If 2nd battery change still fixes nothing, alternator might be bad. A normal charging volt on battery terminals is 15v.