So 2001 4x4 automatic 318. Driving along and its like tranny went into neutral, let off throttle, tranny catches and then it acts like it want change gears. Let off throttle again and it's fine for alittle ways then like neutral again and repeat...... Till I make it home. Today drive to end of road and back, same as b4 but now want go into park? Help!

 

Check the external linkage first. Park is purely mechanical.... it should work regardless.

Check fluid level. Gotta check in neutral. Park will give you an artificially high reading.

After that, unplug the 8 pin connector on the drivers side of the trans, 'bout halfway back. That will disable ALL the electronics in the trans. You will have zero automatic function, see if the truck will move. If it will, take it for a short drive. It won't shift at all until you tell it to.. So, see if it will shift as you move the lever. If it will, its just an electronic problem. If it won't, hope you can afford a rebuild.

 

Check the speed sensor on the transmission/transfer case. Its at a 45* angle on the drivers side. It may be covered in shavings or it could be bad. $18 will get a new one.

Hope that's the problem. Takes about 10 seconds to replace.