94 Sable SLS Wagon Transmission Slippage

Engine = 6 cyl. 3.8L 232 Today's mileage = 160,252.
Jasper rebuilt engine installed on 1.7.2002 at 101,968.
The transmission was serviced on 9.18.2008 at 157,777. Pan dropped, fluid flushed and replaced, new filter. Also, oil change and winter checkup.
Symptoms:
1. Cruise Control fails intermittently.
2. Beginning last weekend: Transmission shifts OK when engine and transmission are cold. Once all are warm: Transmission shifts down OK when coming to a complete stop. Once I take take my foot off the brake and begin to accelerate, transmission slips ,as in Neutral, then catches suddenly and lurches forward.
My local garage has signed a "death sentence" for the Transmission. Is he correct?

Wondering if you are about to be ripped off is not fun. Attached to this email is a link>

http://www.mediafire.com/?sharekey=792324481aa78525d2db6fb9a8902bda

to the Tech manual on your tranny. Rumage around it and see if you can get some ideas first before spending any big bucks.

Thanks DistanceGuy1. Manual downloaded and I'll be checking it out.

(10 minutes later.)
Holey Shamoley. I'm afraid this is way over my head. :)

I have been in these forums for a bit and what I have seen with tranny slippage issues [as you have described] might be taken care of with a tranny flush along with new fluid. Your original post did not mention a flush, but did mention new fluid. When a tranny is flushed all the fluid is exchanged, not just what is in the pan. Was your tranny flushed as well?

Yes it was. Thanks for the "heads up". I amended my original post to include the flush.

Fluid that gets brownish in color and smells burnt has lost its viscosity properties and thus will not do as designed. The flush and fill you did should have taken care of the slippage problem if it was just old fluid. 9 out of 10 times it is heat that kills trannys.