Auto trans fail to down shift?

[GeorgeCovington]

My 98 150 XLT 4.6 started stalling and shutting off very intermittently at about 85,000 miles. This only happened in stop and go traffic when I came to a full stop in drive. It felt like the vehicle was trying to pull more than normal against the brake, then it would shutter and stall out. I took it to the dealer who changed out the Idle Control. We also flushed and changed the tranny fluid and changed out the plugs and wires. This did nothing. I took it back and the dealer could not find anything on the analyzer. I added some Lucas Transmission Fix and my problem seems to be reduced but maybe this is my imagination. I can prevent the stall by pumping the brakes until the transmission kicks down and the truck idles properly. Does anyone have any other ideas?

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[jpdadeo]

Sound like your torque converter is not un-locking when you stop.

[GeorgeCovington]

Ford service offered to replace my transmission (at my expense) but would not assure me that would fix the problem. I'll give the transmission fix fluid a while to unstick things before considering a rebuild on the transmission.

[casey_1]

Potential causes of your problem, listed in order of likelyness (is that a word? )

Low fluid
Internal filter not seated correctly
Wiring short to the lockup solenoid
Bad lockup solenoid
Stuck valve in the valve body
Bad torque converter

A total rebuild almost never would be required for this unless there is a lot more wrong with the transmission.

[1Bad97F150]

TPS sensor?

[turtle313]

I know this thread is ancient but did you find the solution? My '04 is doing this exact same thing.