trans or converter problems?

[sb001]

I have a 98 z28 with 3400 yank stall and trans go shift kit with only 27000 on it. My prob is that at wot the trans wont shift until it hits the rev limiter sometimes and the converter wont lock up in 4th some times. Car has also become alot slower went from running 12.7's to 13.3's. I pulled the converter and sent it to yank to be rebuilt and they told me everthing looked ok. so i had a trany shop look at the trans and they told me that the trans looked good to them. so does anyone have any idea what might be going on? Bad trans? Bad converter? or Bad trany shop?

[TTS]

Sounds electrical, VSS, comes to mind. Take the whole car to someone and explain the problem w/ as much detail as possible. As far as slowing down, no ideas but fix one problem at a time.

[1fastcamarosss11]

if you have a line lock pm me.

[0rion]

Have you had your car tuned for the convertor? You may just need your shift points adjusted with the convertor. Also,random misfires will keep the convertor from locking or staying locked. Common things with a stall.