On my dash, the check engine light is on.....Checked the codes and it shows that the shift solenoid A is bad..... I took it to a transmission shop and they checked it out, and they said that there is nothing wrong with the A shift solenoid..... When the car is first started and ran, it goes through like a quick shift of all of the gears..... I guess that is a good explanation of my problem..... it doesnt slip when driving it, it only seems to do it when the transmission is cold....... Had the transmission flushed, but didnt change the filter..... Maybe if I change the tranny filter and put some good fluid and maybe a tranny additive in it, will that help..... Does the TCC have anything to do with the shifting??????
Thanks guys.....

ok, I am reading on the 87 to 91 bonneville posts and the problems that I am having with my transmission...... I see one that shows to check the modulator, where the vacume lines hook into it...... That if there is transmission fluid coming out of it then it is bad...... How do I check that, and where excatly is that at.... I see where the line runs down to the transmission is..... with a large round part canister part......Is that the modulator???????

No thats your evap. canaster, your modulator looks like a flying saucer with one vac line going to it, its under your air box on the trans. Unplug the vac line and see if its got trans fluid in it, if it does replace your modulator.

A vacuum leak can cause this code. Check the vacuum line to the shift modulator, it may have a leak. Replacing this hose might correct the problem.

Can you give us the actual code #?
I had a customer'* car with a solenoid A code and when we removed the side cover, the TCC solenoid was bad, not solenoid A

The code was.........P0753----- SHIFT SOLENOID A CIRCUIT ELECTRICAL.....I have had the fluid flushed but not the filter changed...... Could the filter be plugged up with crap.... and not letting enough fluid get the the gears or something like that.... or could the tcc switch have something to do with it......
It is more noticeable when the car is cold or hasnt been ran, like when I leave to go to work in the morning, or at the end of the day....... Seems like when I go to lunch it is good......
Come on somebody give me some help on this one.......

That is purely an electrically generated code, so it is either solenoid, wiring or computer.

My guess it that it is a solenoid, but you have to drop the cradle and remove the side cover to see.