Happened out of the blue today. Starts to slip when driving then becomes complete disengaged. Fluid level OK. After sitting 10 mins. I start car & trans engages but only for a few blocks, then scenario repeats. Trans Arrow on dash flashes sometimes but not every time.

Read that it could be shift-solenoid or PNP switch and they are both external to the trans. Any advice?

ADDITIONAL INFO:
Just drained the fluid and it looked awful and I got out a gallon + and I read that it should have been more like 3.5 gts. TD