tranny wont apply overdrive

I have a 94 T/A I just rebuild the tranny a few months ago, but recently I have been crusing down the highway and some hondas have try to outrun me thats fine, let em try, but a few times I put the pedal to the floor like at 70 mph and the car doesn't want to grab a lower gear, but when im by my own with no cars arround it downshifts normally, its pissing me off, does anybody have an idea of what could be?

Rule #1 with a auto tranny rebuild, no beating on it for at least 5-600 miles.

EDIT - Filter and fluid should be serviced within a few thousand miles too.

tranny has like 1100 miles since rebuild, the only thing I didn't change was the servo and the converter every thing else is new

Is this old enough to have the kick down cable? Or new enough to be able to screw up the shift points with a programmer??
Just askin' ...:dunno:

No kickdown cable in any 3rd or 4th gen they had/have throttle valve cables, different animal.
In 94 the 4L60E transmission was introduced in the F body line. This is an electronic transmission, no TV cable either.
You could have a stuck servo valve (no idea how to unstick it on a 4L60E), a blocked passage in the transmission, low fluid, dirty fluid & filter or a transmission on its way out.
Check the fluid. If it is brown or burned smelling, you got problems.
Why did you rebuild the trans? If it was because it "came apart", then you may have screwed yourself by not replacing the converter. I know torque converters are expensive but they should be replaced when you reduild/replace a transmission, especially if the transmission broke down. The converter can/will hold dirt, transmission fragments & other trash in it. Also if the trans shelled out it could have been caused by the converter or the converter could have been damaged by it and is waiting to let go itself.

I rebuild it because the 3rd to 4th piston was broke or worn out, at least thats what the mechanic told me the tranny didn't had 3 or 4 gear, so I rebuild it but didn't change the converter but didt sent it to a shop to clean it, do you know where I can find a corvette servo, cuz I dont want to spend 100 bucks on a super servo and the mechanic told me I could get a corvette one for 50 or 60 bucks but at the auto part they had onle the super servo

Corvette servos here http://www.oregonperformancetransmission.com/performance-transmission/NTP-K51828C.html

Lets hope the converter isn't on the way out now.

ok so I bought the servo but does anyone knows on wich side of the tranny the servo goes??

The near side in the photo:

http://mysite.verizon.net/strey/files/4L60ERebuiltReady.jpg

A smaller servo is great and all, but the better way to get improved shifts is to remove the retract spring inserts form the 3-4 clutch cage and enlarge the passages to the 2nd band apply servo, as well as the relief port in the pan rail, then reprogramming the PCM accordingly. Everyone does the servo swap instead because it is easier, and doesn't require any real work nor analysis of the hydraulic systems.

As for your lack of OD apply, you might need to look at the 3-4 clutch (very rear clutch stack in the input shell of the trans) and the overrun clutch servo. The 3-4 clutch is a weak point in these units, and should be replaced with 6- or 7-disc assemblies for heavy duty use. The overrun clutch servo can stick in the applied position if the clutch is worn (or if the clutch steels weren't replaced at rebuild) and cause a failure of the 3-4 clutch. It looks a little like this when it sticks:

http://mysite.verizon.net/strey/files/4L60OverRunForwardPistons.jpg

thanks man I looking to change the servo for now freakin car is suking all my money