Idiot lights come half-on during acceleration

Check the ground strap between the the engine and the firewall, it can cause a problem like this. It's also worth checking the condition and tension of the alternator belt.

Just dealt with the same thing in my 82 240. i removed the alt. and cleaned EVERY electrical connection. No more glowing. I also cleaned any under-hood electrical connection that seemed suspect. I tend to think it is a grounding problem that got cured when i messed with the alt. I have trouble believing that a weak alt. or bad hook up connection would activate all the idiot lights. then again, i've learned to believe all things are possible when it comes to stupid electrical problems on my 240.

On most cars, failure of the alternator will cause all the idiot lights to come on, just as they do when you turn on the key without the engine running. It's how you test the lights.