car won't start (with extras)

[90RS13]

Ok, so I'm on my way home and at a stop light the engine dies. I'm like, whatever, and try to crank it. Nothing happens. Now, when the when you turn the key on, (not all the way on) like the acc position, the tach was bouncing around like crazy. This is with no engine running. So then I push the car into a parking lot. After I get done pushing forever, I get in to show a guy what it was doing, but now the tachs not moving. Then I crank and it starts right up. Drove around doing some more errands and it didn't happen again. What's up? I can understand the car not starting for many reasons, but I've never seen a tach do that. Anyone know what would cause that?

[uno]

it was getting a signal from somewhere. maybe the ecu is crapping out on you.