So this is my first post of many. I recently purchased an 87' GTA L98 w/TPI (11k miles). One of the things I am finding is at WOT the trans. hits 4k rpm for about 4 seconds before it shifts into 4th from 3rd. It has shifted hard and solid since I picked it up, almost a slaming into gear sensation. This is my first classic sports car so I'm not sure what is normal feel. I have checked the trans fluid and it is clean and full. I've read some things saying the TV cable or vacuum might be the problem. The vacuum lines seems fine (havent seen any cracked or damaged lines). There seems to be multiple schools of thought on how to adjust the TV cable, so I'm unsure which one to try. Any help would be appriciated and I will give feedback if it works for others.