Transmission Slipping A350e

[snake005]

I'm a new owner of a used 1996 gs300, the same day I bought my car my transmission (A350E) started to slip until I had to pull over and had nothing after that... wonder if anyone has any ideas of what it can be? electronic or mechanical? I've searched and found one input on the internet about it can be sensors, or throttle pressure cable.. I cant get access to a repair manual or am I ready to take the car to a shop, I don't trust mechanics and I do the work myself.. so any insight would be really helpful.. oh and I'm going to get a computer tomorrow to check for codes, but if codes pop up, I'll have no reference.. closest lexus dealership is over 100 miles away.. oh, the previous owner put too much tranny fluid in tranny, I have a feeling that is a major factor, I drained it and refilled it correctly, should problems go away? I just ran it a couple days later and the gears started to grab again but then started to slip out.. do I have to drain the tranny dry and do it all over again? or are the solenoids done? A lexus dealership said the computer needs to be flashed...

thanks, Mike

snake005@hotmail.com