1998 Chevrolet Silverado transmission

The torque converter may not be locked into the pump drive, but top up fluid first and re try, if no drive, you will have to take the transmission out and check the torque converter drive.

I didnt remove the torque converter. I just removed the flex plate from it. The trans mission was only moved back about 6 inches.

Have you re filled the oil,

Yes i started the truck after putting 1 quart in. Letting the truck warm pulling the stick. Wasnt on stick added 2 more quarts still a lil low not quite on hatch marks on stick. Adding the amount needed checked it was on the money between the 2 holes on the stick. Ok lets test it......Its in drive gets to first shift point and falls on its face. It surges falls off surges falls off.....Tried several times same results....Then i placed it in 1st off it goes changed to 2nd still working good 3rd same all good then drive it wouldnt float up into it. So it will run through the gears manually but when just placed drive it wont run through them. Wont even make the first shift.

Sounds like a sticking shift valve in the valve body, but if it was ok to start with and you just moved it back, I fail to see why it would start to act up, was there anything else that happened with the trans out? does it have a vacuum modulator valve fitted?

Ok you lost me on that question.....The tranny in the truck is stock and a 4L60E. So any more info from you would be grateful.

i have no vacuum lines on trans just 3 elec plugs 2 square by the shifter cable and the round plug on the passenger side. All are plugged in.

Time to go get the transmission line pressures tested, something weird is going on, so better start with so basic tests, a transmission specialist can tell a lot about line pressures and shift patterns, it is sounding like a vale body problem.