2007 sport trac shifting question

[jackdaniels11]

I've seen many other transmission posts, but none seem to match my problem/question.

My 2007 v6 5 speed thunks going to first gear as I approach a stop, but it only happens when the air conditioning is on and it's hot (good time to use the aircon) and I've driven more than 50 miles.
It has also gotten another symptom that at freeway speeds when I step on it trying to pass, it does a double thump before it downshift.

I just had it reflashed and it seems better, but still does it.

Any ideas?

Thanks

 

[calahan#2211]

How many miles on the vehicle and/or transmission? When was it last serviced? Sounds like it could have some sticking solenoids or pistons in the valvebody. This may sound funny, but, is it full when warm and at idle? could be a bit low... Oh, I almost forgot. A tune up may help also. These electronic controlled transmissions can act funny when the vehicle is not quite up to par and being worked. They know how much torque is coming out of the engine and can sometimes do funny things when torque and horsepower are below the standards. I had a bit of weirdness going on occasionally when my coils were going out on my V8/6R60 combo.

 

[jackdaniels11]

It has around 75k miles. It had the 60k service a while back. I would think that, at that time, they serviced the transmission. I looked for a dipstick, but couldn't find it.
Just had the oil changed last week at the local Ford dealer and they are supposed to check and top off fluids.
It hasn't been tuned up, I thought that at 100k miles it was supposed to get done. My 2002 Thunderbird had to have the ignitors replaced at 50k miles as the check engine light came on. I'll ask the dealer if a tune up might help.
Thanks for the suggestions.

 

[swshawaii]

Check FREE TSB's
http://www.bbbind.com/free_tsb.html

Calibration Update 4.0L - Various Symptoms
http://www.revbase.com/BBBMotor/TSb/DownloadPdf?id=134833