I have a 91 Buick Lesabre,3800-- 200thousand miles, what I an getting is a delay or hesitation at around 48mph. driving up a slight grade, the problem is around 52mph. If I start out in D then shift to OD at 50 mph , I dont have thie problem, car will run fine.
no check engine light. Installed new plugs, plug wires ,coilpacks,fuel filter, and fuel pressure regulator. still having the same problem.
Now i have been told that it could be the Ignition Module, or because my alternater is reading 15 VOLTS.
any help would be very appreciative....

It would appear your attempting to lug the engine while the torque converter is locked up. Mine does the same thing if I try to push too hard on the accelerator while its locked up.

Though I'm sure others will chime in with other possibilities.

Actually, a bit of hesitation in fourth gear with the TCC engaged can be caused by your vehicle needing a tune-up. The 4T60 is weird like that. However, you changed just about every ignition component, so you should be good on that front.

I don't think your alternator'* voltage regulator would cause a little hesitation. Granted, 15 volts is almost 10% more voltage than your car is expecting; however, your car electronics generally don't start acting up until you hit about 16 V (well, according to my stereo'* manual, at least).

Don't forget, your alternator output is inversely proportional to its temperature. On a cold winter'* morning, mine will start at over 15 V (14-ish in the summer) before settling down as it warms up.

Oh, and welcome to GM Forum, Judy!

when ever mine has done that its been ign related did you check for corrosion on the icm tabs? voltage is likely normal if you checked it with a meter, i wouldnt think that would cause the issue anyway

Thanks for all the suggestions,,well heser'* an update, i was told that it migkt be a transmission problem, to drop the pan and see what i could find, change filter and fluid.
well anyhow i did find a piece of plastic in the bottom of the pan, its about 1/8 in thick, 3/8inch wide and about 2 inches long. dont know what it is .

Looks like a piece of the filter.. not sure how those get outside the filter case and into the pan..

This guy found the same thing: https://www.gmforum.com/park-avenue-...ipping-303110/

That'* not a piece of the filter. That I believe is the 4th clutch thrust washer. I have seen that in the pan'* of 3 different trans. Plus, the filter is black, not white like that piece in the picture.

I hope for my own, and their transmission'* sake you're wrong. :(
I know when had those issues I had slipping in 3rd and 4th, and in reverse, I changed the old dirty fluid, and it quit slipping, I wish I had saved the old filter, I'd open it up and see if that material is in the filter anywhere.

:/ I am pretty sure you are totally correct Mike, just found this in an old thread here.
https://www.gmforum.com/1992-1999-91...-w-pix-253684/

I wonder how long the transmission will hold up before either of us have to have it rebuilt?
I suppose if they have the money now it would be best to go ahead and have it rebuilt.