1993 Audi 90S transmission problems

I have an automatic 4 speed transmission. Right now my car is not switiching into fouth gear. It also jumps up and down from 2 and 3 almost randomly. I can rev the engine upto 40k rpm and it will not
switch... However, occasionally if I rev it up to like 50,000 rpm and lay off the accelerator it wil slip into 4th gear...
This problem happened on a wet rainy day while I was on the highway. Before this problem the transmission would slip or jump about 5k rpm before it went into 3rd gear... It still jumps like this now...
I am basically trying to figure out whats wrong with my car. I have had transmission problems with this car for the last 6 years... This will be the third transmission and also third switch...
I think it may be either...
1. The computer? When the car gets wet maybe the moisture builds up in the computer and the switch does not get nfo from the computer. Same problems last year when it was cold and wet... So I got the transmission and switch changed... Problem resolved except for the gear slipping a bit...
2. The switch. Maybe it's defective. This is the third switch and it is 8 months old. (could have installed a used switch) I think gears 1-2-3 are hydraulic and for the tranny to switch into 4th the switch needs to electronically signal the transmission?
3. The transmission. Maybe its broke... Like I said it slipped into 3rd gear and maybe its just finally failing.
4. My theory is that the transmission problems started when some numnuts changed the radio in the car. The electronics have been funny ever since and the electronics may be burning out the switches or the computer.
If you have any ideas please help. With the money I have spent on this car, I feel like I could been driving a new S4 with the sports package... and the 20 inch rimms like Mike Jones...
-Jakub
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I am not sure about your vehicle, but check the wiring to the trans especially at the Vehicle Speed Sensor (if so equipped). Look for moisture, corrosion, broken wires, or murky crud.
BTW I am not too sure you can even rev your engine to 40K rpm either. ;-)
The problem sounds electrical to me that gets worse after moisture gets into the connections. Can you plug a scanner/reader/tester/vag-com into the system to see what is happening?
later, dave (One out of many daves) http://vwdoc1.tripod.com /

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Thanks for the help... I guess I meant 4k revs... 40k is kinda high... anyways I will take it to a mechanic... I don't have time to mess around with it myself... Those guys don't give me the impression like they know what they are doing either... They have all the scanners and what not... I will let them know about the wiring issue...
Have a good day...
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