noob question.

i just bought an 89 si, auto tranny (mistake #1, i know. i just needed a car for transportation right now. i'm looking for a 5spd soon)

the guy had it sitting in his driveway since 2003 and only cranked it up a few times since. i test drove it, it fired right up. the transmission was a bit sluggish in second gear to third but was fine after.

this was two days ago, i drove it 100 miles from atlanta to my house. i've driven it back and forth to work about twice. the tranny has gotten worse, i go up to about 5500 rpm before 2nd gear kicks in. sometimes it skips 2nd gear altogether. i've tried shifting down to 2 when starting out and it barely moves anywhere.

i'm thinking since it was sitting since 03, maybe it needs a complete flush. i've topped it off with fluid but it hasn't helped. you think a flush might be a temporary fix until i get sell the bitch or get a new tranny? or is the tranny just dying altogether

ps - i punched it in 2 and the transmission clunked and started going like normal. it fixed itself for about 5 minutes and then it went back to the way it was. odd?