700 r4 shift problems

I have a 83 s10 blazer with 2.8l and 700r4 trans I pulled the trans to replace seals. Now it wont shift out of first gear. So I jacked up the drive wheel and ran it up and it shifts out of first at 25mph and out of sec. at 50mph I have adjusted the t.v. cable the way it says to by releasing the tab and pulling the cable back and then pressing the gas pedal all the way to the floor. And then checking to make sure there is no slack in the t.v. cable at full throttle. since there is no adjustment on tv. cable other than setting this way. Im unsure of what to do to fix this problem . plus my trans shifted fine before pulling. any help would be greatly appreciated.

Is the transmission electronically or vacuum controled? If it is vacuum controlled, you could have a leak. I had a split vacuum hose connecting my transmission to my intake manifold and my tranny wouldn't shift out of first. This is on a Turbo350 though. And, when the engine is running at high rpm without load, it will have very high manifold vacuum. This could mean that when you have the wheels off the ground and run it, it may be overcomming the leak.

the transmission is not vacum controlled. It has to wires which run to the lockup selenoid . the shifting is controlled by the t.v. cable.

Turbo350 is controlled by a combination t.v. and vacuum.

Jody, I will assume that the fluid is up to the proper level. What I have found out on my own S10 is that when I went to reconect the T.V cable at the tranny I found it tough to keep the cable atached to the spring loaded hook in the trany. The way I,ve been led is . That hook in the trany is the fluid pressure valve, so I have been told. I had to manually adjust the Tv cable, I started with the cable as far foward as posiable, I found that when I moved the cable rearward that my shifts happend sooner.
I hope this will help u out Jody, cause I know how fast a T.V cable can switch H.B.O.

If fluid is at the proper level , and you say that you have checked the T.V. cable I don't know what else it could be . If you hadn't already said you checked all that, I'd say that the T.V. cable came loose and it was trying to shift hydraulically. "Please tell me what you find" .:confused: