94 auto, when its in drive, it bounces back and forth every few seconds. In 3rd, it behaves normally, while its in 3rd, I have to keep the pedal into it to maintain speed.

This happened after a hard hook shift from 1st to 2nd...
guessing a snapped a band, have a data-log from the PCM of driving after the fact, but it shows no codes, just the oddness...

????

 

The band may be slipping, but it's also on in 2nd. Have you noticed anything with 2nd gear? Many times it will show up in 4th first. Does it ever bounce off the rev limiter on WOT 1-2 shifts?
The 4th gear piston in the servo applys the band for 4th. There could be a problem with the sealing ring, or it could be leaking around the apply pin. These., however, aren't common problems.

Frank
CPT

 

I've never had a non-programming foulup related bounce off of the rev limiter in 1-2 shift....
2-3 shift has always been fine...

I will check into the 2nd gear, but it seemed to be fine.

for the past few months I've been hearing a loud clunk in the 1-2 shift whenever the tires hooked properly...I assumed it was time to replace the tranny mount as I tend to break them ever 10,000 miles. The ABS light comes on when it happens as well.

I replaced the tranny mount, but the thunking noise is still there, and today in a WOT 1-2 shift it was a very loud thunk, shifted normally, but now I have the issue mentioned above....it seems as though it will no longer go into 4th gear, except for a moment, and then auto-downshift back to third..but while in third it requires pedal pressure to maintain speed or it decelerates
If I set the shifter to drive (3rd) then it operates normally..

checking out the datamaster log file to see if there are any glaring and obvious issues..



UPDATE...


drove it around and looked over the datalogs, it was ok for a few minutes until it hit temp.

After that it mostly refused to shift from 1st to 2nd unless I let off the throttle completely, didn't have much trouble from 2nd to 3rd, doing about the same thing from 3rd to 4th, reasonably well behaved in 4th...but has trouble getting out of first gear.
datalogs showed it was slipping like crazy in 4th gear at 50-60mph when previous datalogs showed slip RPM being near 0, now it goes up with rpm slipping from 400-2000 when the rpm's are between 2 and 3k and throttle is very low...

almost seems as though I have two problems, or perhaps one is causing the other... guessing the torque converter is shot, as well as the lockup portion of the converter....and/or the 1st/4th gear shared band is toast?