Automatic Transmission - Shaking when in fourth,please help!!

This just started a couple days ago. If i take off from a stop at a steady 1/8-1/4 throttle when it shifts into 4th it chatters and shakes the car. Then it goes away after about 3 seconds. Any ideas,no other problems, every thing else works perfect. I was at the track saturday and accidently shifted into 4th on the spray once.

Best guess would be some converter clutch chatter ,

How serious would that be. It doesnt really both me that much but at the same time i dont want to damage anything else. Would it be an actually converter problem or some kind of weird tuning issue???

well tuning might hide the problem but more than likley the converter clutch has burned , Eventually it will fail if this is true ,

Tcc problem or a check ball thats stuck in the seperator plate would be my guess.