04 Impala LS 80K mi. Intermittent trans issues see below on 2004 Chevrolet Impala

1 - going from stop, you gas it & it starts to move like it's under a strain then a deep internal slam & it takes off. could be trying to start in a higher gear then dropping into 1st when rpm's increase? 2 - randomly has a bump or thump when upshifting under light throttle (all 3 shifts), other times shifts quietly & smoothly. Both problems are very intermittent, doesn't seem to matter if it's warmed up or cold

by in Frederick, MD on March 01, 2013
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1 answer 6 comments
ANSWER by , March 01, 2013
ck trans fluid level and also see if its dark brown. if its dark brown try trans service to start with
COMMENT by , March 01, 2013
Thanks, but definitely not it. Bought in Dec from a Volvo dealer. Took it back soon with these problems, they had for several weeks, couldn't diagnose, put a rebuilt trans in. Now better, but still same symptoms, just not as frequesnt. I know you can get a bad rebuild, but odds of the exact same issues have to be low. I wonder if they really even needed to put trans in it. Could it be some kind of electrical gremlin vs mechanical?
COMMENT by , March 01, 2013
Try a can of seafoam trans. tune!
COMMENT by , March 01, 2013
do you have any trans codes?
COMMENT by , March 01, 2013
thanks for the reply. don't know, dealer is working on it. They're a Volvo dlr, they sub the work out to an independent shop down the street. dlr bending over backwards but I have no confidence in their guy. Trying to get them to work with Chevy dlr or trans shop
COMMENT by , March 23, 2015
my 2004 Chevy Impala has the same problem did you figure out what the Issue was with your car
COMMENT by , March 24, 2015
after they had messed around with the car for about 2 months, I finally convinced them to take it to a Chevy dealer who diagnosed it in 1 day as a pressure control module, no big deal.