1984 Eldorado V8 4.1 downshifting problems
 

I have recently acquired my Dad's 1984 Eldorado V8 4.1 car which as only 65K miles on it and is in very good condition. The problem that I am having is that when driving on the highway for a period of time it will not downshift and the car ends up stalling or lunging at the light of the off ramp. I have pulled the code and it is 29, does that sound correct with what I am experiencing? (TCC Selonoid)

Is this a job that a person and take on or should it be left to the professional?

I have the Haynes Repair manual and it does not address what has to be done.

Can anyone help?

A bad TCC solenoid can cause this issue, but a stuck valve could also. I would suggest removing the transmission pan and seeing if there is an excessive amount of funk in it, and then go from there. If the pan is reasonably clean, a solenoid replacement might just fix it up. Replacing the solenoid is fairly easy to do, but it will also have the internal wiring harness connected to it, so other components(pressure switches, etc,) will need to be disconnected.
Another option is to get a replacement solenoid that simply splices in. They come with quick connects, and are fairly painless to install.
If the pan has quite a bit of doo-doo in it, replacing the solenoid might fix the issue for a little while, but it would not be a permanent solution.
hth