A904 Trans experts I need some advice

[1BAD68]

Symptom's:
While cold, transmission will not shift out of 1'st or 2nd gear until around 5000+ rpm, once shifted into 3rd it will work fine as long as you drive it.

Could this have anything to do with the throttle valve, plunger, springs? (see pic)

The reason I ask is because I installed a Transgo TF2 kit in it and accidently ground off material from the throttle plunger instead of the throttle valve.
I ended up welding material back onto the plunger and grinding it smooth, but I'm sure that it's not the exact length anymore.
Also it could be hanging up in the sleeve until enough pressure builds?

[RD]

are you starting out in drive or 2nd? from the way you wrote the first sentence it makes it sound like you are manually shifting your car.

worse comes to worse, if you need another one, let me know, i can send you one.

[1BAD68]

Starting out in drive but that brings up another symptom that I forgot about.
It will not downshift so I have to manually downshift no matter if its cold or warmed up.

[RD]

it sounds like during your inadvertent modification and remod, you did not get it to its stock form.  this is causing the VB to do exactly what you hypothesized... not enough pressure is being built up for the trans to shift to the other gears. 

it is time to replace the piece with another one. let me know if you need one.

[1BAD68]

Thanks RD
you have a PM

[John_Kunkel]

If the length of the "plunger" was wrong it could be compensated by linkage adjustment.

Sounds more like a governor or stuck shift valve problem. A test gauge on the governor test port can eliminate the governor as the problem.