1999 chevrolet venture transmission shifting hard?

Question

it does not do it all the time seems to do it more when driving in slow city traffic

Answer 1

change the fluid and filter and sustitute 1pt of tranny fluid with one pt of sea foam tranny additive ( sold at most auto parts stores), Once the tranny fluid goes bad it will cause harder engaging especially noticed at lower speeds where the tranny is shifting more fequently through 1st and 3rd gears

Answer 2

I believe you have a vacuum leak on transmission

Answer 3

check your transmission oil. take for a good run on the highway, to clean the carb out..:):):)