My 98 GT developed some issues with accelerating. It seems like it's not downshifting when it should. When casually accelerating from 45 to 55 , it sounds like it's gonna stall. If I tap on the accelerator a few times to get it to downshift it accelerates fine. It sometimes does the same thing at lower speeds and on occasion I think it'll get stuck in 2nd at a stop light--it'll idle really rough (@ under 1k). Is this a $1k+ transmission issue I'm looking at?