What's happening with my Camry?

Two months ago when I was driving my '07 Camry (about 98,000 miles, automatic), it started freaking out - the dash lit up and the speedometer stopped working, as did the heating/cooling and the compass. It only happened when my foot was on the gas, but the power/function of the car seemed totally fine. I had the battery and alternator checked that same day and they confirmed both were functioning normally. After that, the issue completely went away and didn't happen again for two months - until two days ago. It's now happening every time I drive it.

The only other info that might be relevant is that the radio is currently disconnected. About 6 years ago, I had an issue where I stuffed my trunk too full of stuff, and it apparently damaged a wire. After that the battery died every few days and the only fix that wasn't $2,000 was to have our mechanic disconnect the wire.

Any help would be so appreciated!