Rough take-off from stop

Hello all. I appreciate any advice.
I have a 98 Taurus SE with the 24 valve Duratec engine (I think), about 150,000 miles on it. Recently, the car has been very jerky when taking off
from a stop or near-stop. It's as if the transmission can't find the lowest gear or is jumping back and forth from a lower gear to a higher gear. The RPM needle jumps when this is occurring. If I start from D2 and manually shift to D, the problem does not occur.
I was told by a transmission shop the problem was the throttle position sensor, so I had that replaced, but it didn't fix the problem.
Suggestions?
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semisweetchick opined in

How does Cruise control do? Does it keep your car at a steady speed?
What does the speedometer do... is it steady?
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- Yes, I'm a crusty old geezer curmudgeon.. deal with it! -

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Thanks for your help.
Cruise control maintains a constant speed, except on downhills, where it doesn't restrict the speed at all.
The speedometer needle remains steady, though as I said the RPM needle jumps.
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So then... any fluctuation in RPM (by engine sound) OR tachometer while in park... or stopped at light/sign?
Hard to start? Rattling under acceleration?
semisweetchick opined in

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First, my sincere apology for the multiple posts. I don't know why that's happening. I'm certainly not a newsgroup newbie.
There is no fluctuation in rpm at idle, while stopped or in park. It's not hard starting, and it accelerates fine after the initial shifting problem. I haven't noticed any hesitation if I have to tromp on the accelerator.
One thing I do recall, but I forgot to mention initially, is occasionally when slowing down to a stop (braking), there will be a very slight clunking just before the stop occurs. This doesn't always happen.
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Thanks for your help.
Cruise control maintains a constant speed, except on downhills, where it doesn't restrict the speed at all.
The speedometer needle remains steady, though as I said the RPM needle jumps.
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semisweetchick wrote:

about
taking off

lowest
The
manually
position
How about routine maintenance, like a new transmission filter and fluid? What does the dipstick tell you, is the fluid low or brown? Did the tranny shop check this?
Matt
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Routine maintenance has been done all along. The tranny shop said everything looked good, as far as the fluid color and level. I pulled the dipstick myself, and the color looked fine. I also smelled the dipstick, and it didn't smell burnt or anything. I'm not sure when the last filter change occurred -- I would guess within the past year.
Thanks!
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My husband and I thoroughly tested this problem last night, so I have a much better description of how the car is behaving. Also, I determined that this Taurus has the AX4N transmission.
When starting in D from a stop, the car is doing one of two things.
First, sometimes it shifts 1-N-2-N-3. Normally, the time in neutral is a fraction of a second, but sometimes it's about a second-and-a-half. When it's neutral for the longer time, the RPM needle jumps. The speedometer needle remains level.
Second, sometimes it feels like it's not slipping into neutral but actually is shifting very slowly and not smoothly from 1-2-3. After it reaches third gear, it shifts fine. In this scenario, the RPM needle remains steady while shifting. The speedometer needle remains level.
Any new thoughts on this?
We have taken the car to a transmission shop today, so I will update this thread with any diagnoses/solutions.
Meantime, I'm still appreciative of any thoughts from y'all on what this might be.
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