I have a well taken care of 01 that has started acting as though it has a loose ground wire or faulty pin/terminal connection. Cleaned batteries, found loose groun bolt on the drivers side under the dash, checked the chassis/cab and engine/chassis wiring and verified that they are secure.

Symptoms: intermittently,with the truck running, foot on the brake (Stopped), in gear (auto), speedometer hovers at 10 mph and randomly moves back and forth between 10 and 35 mph, tow/haul indicator on shift stick flashes, and radio cuts out. When this happens, if i apply throttle, the engine does not respond with normal power. On occasion, the entire truck will die.

Has anyone else run into this? Troubleshooting electrical can be a nightmare.

 

When you state , cleaned batteries, I believe its safe to assume the engine is a diesel?
Also , the shift stick, light you are referring to the overdrive lite? Based on these assumptions; which could be all wrong, but, when the overdrive lite is flashing it usually says there is a problem with the trans. As a starting point, remove the harness plugs at the trans and check those plugs and pins for corrosion. Back circuits through corrosion can drive a tech nuts. If you see green stuff at the pins or plug you found something worth looking into. Also a good penetrating oil will usually clean them out.
Let me know if you find anything. Thanks, hanky