Ever since my top end job I've had a little problem. While cruising 40 ish+ and let off the gas it feels like it is missing (car slightly jerks forward and back) untill you push the gas again. Is it possibly from having a stock stall ? Any ideas please

 

If you are in forth, because of the low RPM, the convertor is probable locking in and out..... My stock one did that too...

 

Actually in 3rd but happens in forth as well. I think your right though about the converter. Anyone else have a idea or suggestion?