Changing transmission oil

Transmission problem
1998 Buick Lesabre 6 cyl Front Wheel Drive Automatic 94K miles

I just changed tranny fluid and filter at 94,000 miles on my 98 lesabre. While in "D" transmission will slip under heavy acceleration from a stop, yet however while in "1" there is no problem. I know I took all the metal and friction stuff out and I would like to know if there is a band adjustment or something I can do? There are no service manuals at my local library's with this info so if anyone can show me a website or tell me how to do this I would greatly appreciate it.

Thank you,
Dan

I used the next grade better fluid and it is at proper level. When I cleaned the pan there was dark colored material lightly coating the pan and all over the magnet. I only owned the car for about 15,000 miles so I don't know when it was last serviced.

I also replaced the radiator shortly before I did the the tranny fluid and the coolant level has not changed. If there's anymore info you need just let me know. Thanks alot I appreciate your help

Yours truly,
Dan

PS It's not so much a not holding gear slip it's more like a shudder when you put it in drive and immediatly hit the gas

I recently bought a 95 LeSabre with 101,000 miles on it. I don't know the history of tranny fluid changes in the car, but my personal mechanic says the fluid is burnt and that I should have it changed, while I do trust his opinion I have run into taking it into a Jiffy Lube and them telling me they highly recommend I don't change it, so I got scared and didn't have it changed. I have an appointment in 2 days to try to get it done again. Do you think I should do it, or leave it be? I get mixed answers from everywhere I look. Some saying it's okay to do, some saying no don't. I can't afford another car if I don't change it and it fails due to previous owner negligence, or thousand dollar repairs either. What is your advice on the issue? The car looks pretty well maintained at purchase time and was driven by an old woman who passed away(don't know if that matters), and I will add that the car was used in a high altitude area. About 7500 feet above sea level, where I live also. Estes Park, Colorado. Thank you.

What would possibly make the transmission slip first thing in the morning when the weather is cold? At all other times, it shifts fine. It's been doing this for some time, so I recently had the trans fluid changed and flushed. Now, it slips a little more, first thing in the morning. Instead of slipping for 20 seconds after starting, now it slips for 30 to 45 seconds.
Any ideas?
Thanks for your help.
Allen

99 Buick Lesabre 141k miles 3.8 series 2 engine. I changed transmission fluid, using dextron 3 as recomended Replaced original pan gasket which was leaking. Transmission is operating as always, smooth shifts and forward /reverse engagement. However when accelerating from a dead stop faster than usual the transmission ratchets or shudders but continues to pull. This condition reminds me when as a kid my chain on my bike would slip if I started off fast. This is the only problem noted. Trans dip stick shows full acually a bit low but not excessivly. Any suggestions? Thanks

Are you checking the fluid with the car on and in nuetral. If not you should, and you will probably find that its lower than you think. If all this is ok you should check if your TV Cable is ajdusted correctley.

Check the TCC module. The shudder could be from the torque converter not engaging fully. The TCC module controls the torque converter and power distribution. Lesabres have always had a problem with the TCC module. THis can cause a shudder (especially in overdrive) and when you need power in flooring it. THe TCC module in your model is to small to handle the power from the motor. AAMCO has an upgrade they can install for $300. THey bore out the old TCC hole and input a bigger one. Or you can replace the one you have and get another 30000 miles out of it or so. It fixed my problem.