Morning trans issue with the 420

[Ascension]

Opposite issue of the common one. It engages reverse as it should I back out and down my drive way stop drop it in drive and feel it engage but when I hit the throttle it has a hitch like it starts to move then suddenly drops out of gear for a second then slams back. Only done it a total of 2 times sice I have had her until today and both when cold and then shifted absolutely normally. Has suddenly done this twice today now the temps have dropped and this issue now has my attention. Last time I drove it I rolled in down one notch and waited a sec to make sure it was fully in gear and it did the same thing after sitting for a couple hours and cooling down. Just a slight move then it seemed to bounce out of engagement and right back in.
Once it cycles that one time in and out then engages everything from there on is absolutely normal. This one is not your normal hard seal morning sickness issue where it slips till it warms so what am I dealing with here??
Anybody else seen this with one of these units?

 

[gsxr]

If this ONLY occurs when cold... it is a somewhat common issue. I've had it on several cars. MB refers to it as a "double engagement".

There is a TSB and special fluid if you want to gamble on that fixing it. I tried the special fluid in one car and after a couple thousand miles, there was a noticeable improvement.

TSB PDF:
http://www.w124performance.com/docs/mb/transmission/trans_dbl_engage.pdf

 

[Ascension]

If this ONLY occurs when cold... it is a somewhat common issue. I've had it on several cars. MB refers to it as a "double engagement".

The description from the TSB in that link looks to be dead on what I am experiencing here thanks Dave! When you drop it in gear you feel it engage but you first accelerate in drive when cold it starts to move suddenly disengages then quickly slams back in gear then everything is perfectly normal from that point on.
Will dig a little deeper on this issue. Wonder if a change to D4 would help any?
I can find no evidence that this unit had ever been changed when I got the car right at 95K. I changed it and the filter but almost got caught by pretty good thunderstorm before I could drain the converter. I used the Castrol Dex Merc and ran it another 500 or so then did a second pan drain and refill. Plans were to hit it with one more pan drain and refill in about another 1000 from here ( have just over 98K right now on her) then a full change to synthetic at the next oil change at 104K which would put it just under 10K since the 1st fluid and filter change I did.
Suddenly rethinking where I need to go here so any more advice from others here who have dealt with this issue would be appreciated.
My main concern here is breaking something when it slams back in on that 1st double engagement.

 

[Ascension]

Went back and pulled all the service records for the car. Found a dealer service invoice that I had missed showed the 30K service. The F&F was indeed changed at the dealer for the 30K service in Jan 98 at 28K. Can find no evidence that it was ever changed again until I got the car so that would have put right at 60 on the last fluid /filter change before I got her.
I noticed something odd on the 30K invoice in an item listed as 1-1400330-1 Trans Trea. Can anybody here who knows dealer invoice codes here tell me what that was?
Reason I ask is the service bulletin says that once the special fluid is used in a unit that has an issue with "double Engagement" it must be used from that point on. I'm suspicious here as this issue only surfaced after I serviced the unit and now that the weather is suddenly getting cooler has gotten worse. Other than the double engagement issue at times on the 1st cold start the trans is acting absolutely normal.