700-R4, TCI constant pressure valve body, TCI vacuum kit for lockup converter, BTE 10" 3K lockup converter. Mainly street driven, problem popped up again, getting worse. It's going to around 4K rpm before it will shift out of 1st. When it does, it skips over 2nd, goes to 3rd. I also noticed the other day the torque converter was dropping in/out of lockup at light throttle, not what it's been doing. I don't know if that's related or a different issue. Just dropped the pan, changed fluid and filter with no change. While the pan was down, I bypassed the 4th gear pressure switch, put vacuum on the lockup switch, and solenoid does work. I had similar issue before. Called TCI tech and was told to pour in a bottle of Lube Guard, jack the back wheels up and run the transmission through the gears. I did that and the problem went away for a while, but it's back. I did use Lube Guard when I put the new fluid and filter in. This is a constant pressure valve body. TCI tech told me to adjust the TV cable to where the piston is all the way back when the throttle is wide open. Thanks.