4EAT issues

[fedup]

I have a 94 Emerald SVX FWD. 3rd and 4th began to slip on me about a week ago. i went to the Family Values tour across town last night, and on my way home i heard my engine over my radio with the windows down. This being odd, i glanced down at the RPMS and it was about.. 5,5k doing about 70. upon further driving "diagnostics" I have found out that the Tranny won't hold 3rd or 4th, at least not when you give it gas. It will shift into them, just when you give it gas it'll rev up til it redlines then will drop down into 2nd.

Do i fear the inevitable of a rebuild? or could this possibly be something else less major?