About a month after changing my trans fluid, (drained pan, changed filter, added about 6qts of synthetic ATF4), it has developed a little glitch in the shifting from 1st to 2nd. Under light acceleration there is a significant surge forward and drop in rpm at about 1500rpm for a split second and then it continues to accelerate normally. It also does it in manual mode. It will also do it in manual mode starting in 2nd gear. Under hard acceleration it doesn't seem to do it. It feels like the torque converter is locking up for a split second and then releasing. There are no CEL or codes. Any Ideas?

 

what brand fluid did you use

 

I used Chevron ATF4 full synthetic.
thanks