Greetings to all you Mercedes Benz fanatics from New Zealand

Car is 89 W126 300SEL done 149K well serviced (and loved)

OK here we go !
Recently when the engine/trans cold no problems, however everything got hotter when say, turning at an intersection, the auto trans started to drop from 4th into neutral (instead of 3rd) then after 8/10 seconds bang (and I mean bang) into 3rd.

Had auto trans rebuilt by local MB Agent and had everything that needed replacing replaced. Normal wear, nothing visible broken.

Now the following is happening

When engine/trans cold, everthing perfect. Better than before.
As verything gets hotter the following occurs:

- trans drops from 4th to neutral instead of 3rd
- car creeps forward in neutral
- car strains in reverse, feels like brake on, trys to go forward !
-manual change from 4th to 3rd (with gas on) goes to neutral 8/10 seconds then bangs to 3rd

Line pressures to cooler OK and we have tried a another valve body from an identical trans. Trans stripped down again, all clearances etc checked...nothing !

MB (DC) stumped

Any ideas greatly appreciated

The Buzzard