We just changed our transmission filter & everything seems to be working fine now but the rpm is going to high and won't shift after 3rd does anyone know what we should do?!

Depending on the transmission.Many gm trans. have an A and B switch in the trans. When you removed the trans. pan , is it possible you knicked the switch (a miniature motor really) in the trans?. A controls gear 1 and 2. B gears 3 and 4.The tabs on these motors are very delicate and break off them easily.

http://www.pepboys.com/product/details/9306314/00166/parts/drivetrain_ cv_axles_transmission/automatic_trans_switches_relays

http://www.pepboys.com/product/details/9791756/00166/parts/drivetrain_ cv_axles_transmission/automatic_trans_switches_relays

Yes I had the shift problem before I changed the filter that's why we changed the filter, & it's running smoother and seems better but it won't shift gears after 25-30mph & what's the ecm & how do I do that?

& fluid leval is fine we put 6quarts

& if we knocked one off those switches off how would we know and how do we fix it?

The switch is easy to check, once inside of pan again. Look at the 2 wires on the switches ( they're actually little electronic motors). If any tab is broken replace it. It is held on by a small fastener behind the actuator. Check the link I shared and it should show the switch upclose as well as hardware. It sounds like the B switch.Classic symptom you describe.

is it the same thing as a solenoid?

please send link again it's not letting me go to it

I think it's either the 3-4 accumulator spring in the valve body maybe broken or the 3-4 clutch discs in the transmission are worn out. Anyway I just found a Tech Manual for your trans. http://www.grail-ss.com/GRAIL%20Website%20Files/4L60ETechGuide.pdf