Sluggish Engine / Vsc / Check Engine

[Dgoude]

I have a '99 ES 300 with 135K miles on it. I had problems when I bought the car in '02 with 23k miles on it with the VSC and VSC Off lights coming on spontaneously. I took it to the dealership 5 times and they finally decided to replace the on board computer. This solved the problem until recently.

The last few months the problem has returned but this time with other symptoms. Sometimes if I punch the gas, whether just starting off or hitting it hard to accelerate, the engine bogs down for a few seconds and then catches. But recently when I've been getting onto the interstate and have had to accel quickly the VSC and VSC Off lights have come on (sometimes with the Check Engine Light and sometimes not) and the car is very sluggish. It was sporadic at first and now it is every time I have to really hit the gas. If the Check Engine light comes on with the VSC and VSC Off lights I have to disconnect the battery and it all resets and goes back to normal until the next time. If the Check Engine light doesn't come on along with the others, all I have to do is shut off the engine and it doesn't come back on again until I have to accel quickly again.

I am not a mechanic by any means but do like to DIY and have the Haynes manual. I've changed my rotors before and spark plugs (in a previous car) so I'm not afraid to get my hands dirty if it's something I can do myself. Can anyone help here?

Thanks,

Dgoude