I have a EF XR6 with a auto tranny that has been giving me the willys.
Generally the car is good but once the car heats up to operating temp i get intermittent shifting issues ( not all the time, only sometimes).

I'll be driving down the freeway at 100k's in Drive and then all of a sudden the gbx will jump into 2nd gear and sent the revs rocketing. sometimes it will change back to 4th after a few seconds but otertimes it will stay in 2nd gear. If i change the gear stick between D and 3rd it has no effect. Then when i change back to 2nd it will act as though it is in drive.

Other times i can be driving along and the car will neutralise. and i can shift between 2-Drive with no effect. only when i go to 1st it picks up first gear and away i go.

The oil and filter is good. I replaced but this didn't fix the problem...
Anyone had any simialr issues?

Sounds Like the S2 solenoid playing up

Gassa

As above i had 4 of them replaced in mine. Take it to someone who knows what there doing. May not need a full rebuild if it changes correctly at other times.

Regards

Basics first... Check the plug on the neutral switch on the passenger side of the box. Make sure its in properly and the contacts are clean.

Next try to get hold of a known working neutral switch and swap it over and see if that improves things. They are simply a resistance wheel and when they die they can do all sorts of weird things, even along the lines of what your explaining.

If that no fix, then its something in the box.

I'll give it a go.
Is there a sensor for the gear selector position that could be playing up?

The gear position sensor is in the neutral switch. The small white module on the passenger side of the transmission.

When these stuff up, they have been known to cause the issues you are describing.

Yep it was the neutral switch