2002 dodge stratus transmission

i hear that stratuses have always been built with bad transmissions. im purchasing one off of my friend that just had it rebuilt about a year and a half ago, but now it downshifts pretty hard from like 3rd to 2nd gear(when coasting its between 35 and 30 mph). thats the only problem it has. the place he had it rebuilt at said it could be two things, a solenoid pack(which would cost 600 for them to do 100 for me to) or the computer needs reset by the dealer. if it was either of these wouldnt it have other problems shifting?? any help would be greatly appreciated!